About half of the specimens have five tentacles in each interradial group, while the others have three. Manubrium.— The manubrium is short, reaching the level of the bell cavity; the mouth is surrounded by four separate lips, with slightly fimbriated lips (pi. Tentacles.- The arrangement of the tentacles is characteristic, there are four large perradials and a considerable number of many.
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YOUNG STAGES
Agassiz (1865), by Maas (1904&), and by the writer (1909c), consists of a series of vertical folds at each interradius, becoming oblique or even transverse near each ray, and within the plank of the North Atlantic specimens. .
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Manubrium and gonads.- The manubrium, like the bell, ercubic, fills almost the cavity of the bell, and is attached to the subspace. The gastric part of the manubrium hangs below the middle level of the bell-cavity, and it. Except for size, the tentacles are structurally all-similar, and there are no very young in any of the specimens.
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UNION BAY
Several small segments of the margin are destroyed, but where it is intact, as it is over most of the circumference, the ratio of tentacles to canals becomes just over 3:1. Unfortunately, all the specimens are in poor condition, the umbel is badly damaged and the rim is so nearly destroyed that not a single tentacle or sense club is intact. The specimens are so battered that it is impossible to add anything to the earlier accounts of the species beyond that they all show a well-marked apical thickening or apex node.
Most specimens are in good condition, except that the tentacles are briefly broken off. In the original species of the genus, hrunnea, the tentacles are arranged in several rows, but in a new species in the collection this arrangement is less developed, and in young stages (p.49) the tentacles are arranged in a single row. Structurally, the few tentacles that remain intact are of the usual Trachynemid type, being massive, with a nucleus composed of chordate cells, and with the pigment confined to the entoderm.
Peripheral organs. In both specimens most of the tentacles have been briefly broken off, but their stumps are well preserved in both, and the tips are especially clearly of the uncontracted type. In the smallest specimen (14 mm) they are attached to the canals about one-third of the meridional distance below the apex; in the 19mm. All specimens, as might be expected, have gonads, for these organs appear when a diameter of 3-4 mm is reached (Maas, 1909); and they.
The specimens add nothing to our knowledge of the species, except the record of their occurrence.
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This specimen is a female with large eggs and shows that the reason the eggs in the large eastern Pacific specimen were white (1909a, pi.9, fig. 4) was that the upper tissue had been torn away, or at least that the pigment had been destroyed . These kudoxides, in both, the bract is 25 mm. long, agree very well with one of corresponding size from the eastern Pacific. In the Biscayan writings of plicata (1911&), Ifoundwhatudukentobeatjq^special nectophores, in addition to gonophores, in a cormidium.
The nectophores in the present series (pi.5, Fig. 10) correspond in their short, broad lines to those of Biscay and the eastern part of the Pacific. Stem and appendages. Only young siphons, gonophores, and bracts remain attached, and none of these are sufficiently advanced to show whether there is an important difference between them and the corresponding organs in Cymbiformis, nor did the eastern Pacific series prove to be any more useful. In none of the eastern Pacific specimens was the somatocyst terminally dilated, while in the Biscayan series it varied from a slight thickening at the tip to an ovoid terminal swelling (pi.5,fig. 11).
Fortunately, the apical part of the subumbrella of each is intact and shows the network of subumbral canals, which is the most important characteristic of the species. The four bracts captured with the nectophores agree very well with those collected with the type specimen (1911&, pi. 3, fig.. 6), and the fact that the bracts of this type have been taken twice with the nectophoresis, is almost proof positive that they belong together. It appears that there are large differences in the degree to which the spine is developed on the ridges that bound the facets. 1897&) shows numerous pointed spines in these regions, and the Biscayan specimen taken by me was likewise slightly brittle at the edge of the facets.
In the younger nectophores of the pentacanth, the sinus is smaller. pi.5,fig.8) thaninspinosa at a corresponding stage, and as the bell grows it becomes more and more narrow, taking a heart shape (pi.5, fig.
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But there is no trace of anything answering to a somatocyst in any of the many posterior bells. It seems necessary to separate the Siboga and Albatros specimens specifically from the Mediterranean ovata, because the base of the posterior nectophore is provided with large and conspicuous teeth, whereas in the ovata this region is represented as ringed (Keferstein and Ehlers 185, clearly , such as those. ridges at the top, and hydroecium, both of which are characteristic .
The characters that separate pacijica from all specimens of the Atlanticumbella yet described, and all that I have studied, are the tubercle on the upper surface of the disc, the larger number. We especially need series of growth stages of the dodecabotrycha type, and large series of the adults of both, to. In the eastern Pacific specimens there was considerable variation in the width of the furrows, which were generally wide in large, narrow and small specimens.
The general structure of the peripheral canal system has been described by Vanhoffen (1902a) for valdiviae, hyMnhs (19046) for hairdii and by me (1909a) for wyvillei. But the two extremes are not discontinuous, for in specimens from Puget Sound and from Sakhalin Island the outer part of the circular musculature. As explained above, the features that are important in this regard are the shape of the marginal lappets, the structure of the musculature and the color.
But in the large one the branching and anastomosis of the per- and interradials is considerably more complex than he shows it, although sothanitis in Philippina CNIayer, 1910). Duct system.—In the large specimen 91 ducts leave the stomach, but by the branching of the rhopalar ducts there are about 140 at the margin.
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34; The same is true of Pandea rubra, recorded from the Bering Sea and off the coast of British Columbia, and it is debatable whether it is single. Inthefirstplace, cosmopolitan "interconnecting" species, belonging that is, for temaSoplank- ton, halicreaspapillosum, aeginuragrimaldii politan, are at least widely distributed in both the Atlantic and the Indo-Pacific. These are Heterotiara anonyma, which is widely distributed in the intermediate depths of the Indo-Pacific, but is not known from the Atlantic; ProhoscydactylaJlavicirrata, a Pacific species which finds its closest ally only in the other members of the genus, ornata,^one or other variety of which is recorded from various places in the tropical Atlantic and in the Pacific and Indian Oceans; Gonionemus vertens var.
As might have been expected on oceanographic grounds, it is clear that the medusa fauna of the Bering Sea region has been recruited from two directions, with a component from the warmer waters of the Pacific on the one hand and a component on the other. Most leptoline species of northern origin are known from the region extending from Cape Codtos-southern Labrador, while one, Eutonina socialis, occurs in the North Sea; that is, they are boreal rather than purely arctic, although several are known from arctic stations; and this is what we might have expected, for in summer the temperature of the surface water in the southern part of the Bering Sea is from 50° to 57°; that is, about as much as the water in the northern parts of the Gulf of Maine on the coast of New England is considerably warmer than the surface water of the Labrador Current off Labrador. However, since none of them have ever been recorded from arctic temperatures, it is safe to assume that they colonized the Bering Sea from the south.
Islands, in the Bering Sea and in the Sea of Okhotsk, from which one or the other of the two species was taken (in six hauls the two were taken together; each was also taken in the trawl). On the other hand, both were conspicuously absent from the intermediate features of Japanese waters, nor are they represented in the extensive collections made of the albatross off the coasts of California, British Columbia, and southern Alaska, which have passed through my hands . In the Atlantic, too, these two species have only been taken at remote northern stations, although the National, Valdivia, and Prince of Monaco expeditions might have expected to discover them in the warmer parts of the Atlantic, if, as common there as in the Bering Sea, they are such genera as Halicreas, PeripJiylla, and Atolla.
We cannot trace the cold-water medusa along the western and eastern sides of the northwest Pacific Ocean as well as we would like because we know very little about the medusa of the American coast between the Aleutian Islands and Puget Sound.
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Cyanea capiUata, Aurelia limhata, StauropTiora mertensii and the genus CTirysaora are also known from the southern end of Sakhalin Island, in addition to the genera UrasMmea, Nemopsis and PolyorcMs, recorded by Eashinouye. Catahlema multicirrata, CJirysaora helvola, Sarsia tubulosa, Phacellophora amhigua and the peculiar Stauromedusa Thaumatoscyphus have also been recorded by Kishinouye from the Kurils. In examining the records of the Albatross from the Sea of Japan we are confronted with the rather surprising fact that, although the intermediate 1.5 meter net and the small plankton nets were used at 15 of the 86 trawl stations occupied, the medusae in only three hauls were caught.
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A very different situation can be seen with the leptoline forms, because the list does not include any of the leptoline hydromedusae that are most characteristic. But in the case of the holoplankton species, this bar only works in winter, because they are brought to Japan by the Kuro in summer. Unfortunately, we have virtually no data on the jellyfish fauna of the east coast of Nipon, north of Yokohama Bay; Indeed, I have not been able to find any definitive proof; but we can safely assume that before Tsugaru Straitis reached the tropical contingent.
An interesting parallel can be drawn between the pelagic coelenterate fauna of the northeastern coasts of Asia and the northeastern coast of the United States. NewEngland shares certain striking oceanic phenomena, both bathed in winter by cold, almost arctic waters of northern origin, which in summer are periodically displaced by the northward oscillation of a very warm current, the Kuro Shiro in the Pacific, the Gulf Stream in the Atlantic. On the Japanese coast the warm current has an almost continuous influence during the summer; but on the south coast of New England its full effect is felt only occasionally, though it.
Along the coast of Nippon, in the region of Sagami and Suruga Gulf, the annual temperature range is from about 50 °. In both regions, the warm current brings rich tropical oceanic pelagic fauna in summer; but that leaves Nova. England, and probably also Japan, in autumn, when the warm waters belonging to them recede.
In the cold season, the process of distribution is reversed, the warm water species retreat, the cold waters move to the south.
BIBLIOGRAPHY
We do not know how far south the Boreal Medusa extends along the coasts of the United States in winter, but several appear frequently in Woods Hole and in Narragansett Bay during that season, and I have myself seen the waters of Pamlico Sound in January ( just a few miles north of Cape Hatteras), full of the dark red Northern Cyanea. after prolonged northeasterly storms. In Japan, as explained above, the boreal species appear in Sagami Bay during the cold season, and it is probable that they advance even further south.
