Ubiquitous, on every rocky part of the coast of San Jose and Pedro Gonzalez Islands, often in countless numbers. A small form of this species is known from Pacheca Island, the northernmost of the Pearl Islands.
8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I06
A third species, much more strikingly conical in shape and of medium size, was found only in small numbers, and usually in a young state, on the mangrove roots. This small species, about half an inch long, was found in extreme abundance on and beneath the drift in the Rio Marina swamp beyond.
10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I06 the sand barrier at its mouth, especially on the rotting fronds of the
NO. 6 MOLLUSKS OF SAN JOSE ISLAND MORRISON TI
12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I06 The extinction of some of these species of the family Amnicolidae
NO. 6 MOLLUSKS OF SAN JOSE ISLAND MORRISON 1
Aperture less than 0.4 shell height, ovoid, slightly narrowed above, evenly rounded below, entire with continuation of lip over parietal wall. Males with a distinct simple margin attached to the right side of the neck, slightly behind the right tentacle. The absence of this genus from San Jose Island is noteworthy, considering its distribution in the West Indies.
Animal as described for the genus; in the male with a prominent appendage ridge on the right side of the neck. Animal with a prominent pigment band across the tentacles at their distal third, with a simple border far left on the right side of the neck, a little behind the right tentacle. The type was personally collected from rocks in the rapids of the stream leading to the northwestern mangrove swamp on SanJose Island, Archipielago de las Perlas, Republic of Panama.
Bottom white, thin distal half lightly pigmented, attached just behind right tentacle and just to right of midline, on back of neck. 542159, were collected in person in the stretch just above the tidal waters of the Rio Mata Puerco, San Jose Island, Archipielago de las Perlas, Republic of Panama.
22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I06
The habitat zone for this species in this stream consists only of the last rapids of the stream just above the lagoon. The whorls of the low spire are slightly shouldered, separated by a moderate suture that becomes shallow near the opening where the shoulder angle disappears on the body whorl of adults. One pigment band is about at the distal third of the tentacle, the other is.
This Rio Marina is a large stream that opens in the middle of a long sandy beach on the eastern side of San. The shell is conical to helical, usually keeled at the periphery and with spiral cross-sections that may become obsolete on a base that is somewhat flattened. This new genus has spiral lirations similar to those of the Cochliopina group, accentuated in the direction of the peripheral keel and a somewhat flattened base of the body whorl.
Core rolls i^, smooth (worn in type); postnuclear whorls finely and regularly spirally striated, peripherally carinate, and wound so that the suture is in the chamber of the preceding whorl. Aperture subtrapezoidal, oblique, carried far forward on parietal wall, entire, lip edges confluent with moderate callus on parietal wall.
26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I06 heavily pigmented, and with a very small appendage on the left
NO. 6 MOLLUSKS OF SAN JOSE ISLAND MORRISON 2/
2 — 2 the genotype
Light-colored, very little pigmented, with a small branch on the left side (front) near mid-length (in contracted specimens). Aperture subpyriform, entire, apertural plane oblique, somewhat sinuous at subangular base of columella. A generally light-colored animal with a black snout and a black band down the middle of the tentacles and a black spot at their tips.
The rim is light-colored, with a pigmented area along its middle on the left or curved side in the region of a single small appendage, and with a functional tip that is not pigmented. Unlike the members of the genus CocJiliopina found in San Jose, this species is not confined to the narrow zone of the stream above the mangroves, but lives almost to its source in all arms of the stream. It was collected in a smaller northeastern tributary of the Rio Mata Puerco mangrove swamp, which also suggests that it probably lived in the Rio Mata Puerco system before the main southern stream and this northern tributary were isolated.
Under certain conditions, as in the estuary of the Rio Mata Puerco, two of the species are found on the sandy mud, out of the water most of the time, between times of high tide. On the other hand, the group was represented by all four species known from the Panamanian region in the Rio Marina marsh.
30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I06 individuals of each species from different mangrove swamps, as much
NO. 6 MOLLUSKS OF SAN JOSE ISLAND MORRISON 3
32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I06
PULMONATA BASOMMATOPHORA
It was found twice (only once in number) on San Jose Island, in the same ecological habitat. It was active in the early morning out of the sun, crawling among the cobbles and taking shelter when the sun came out dry from the wet beach cobbles. Collected in small numbers on the margins of the mangrove swamp on both the east and west sides of San Jose, near the mouth of the Rio Mata Puerco and the Rio Marina.
One collection of several hundred specimens was taken near the mouth of the Rio Marina, where they were abundant and under drifted, mainly decaying coconut leaves. This species is very close to D. globulus (Orbigny) from Guayaquil, Ecuador, also reported from Tumacao Island, Colombia, but differs in the heavy parietal callus and teeth. The species varies considerably in the largest collected series (several hundred specimens); the difference is mainly in the degree of development of the columellar fold and occlusion of the opening and.
34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I06 DETRACIA STRIGOSA (Martens)
There is one broader, very dark band below the suture, a light band at the periphery, and three narrower dark bands almost equally far below. The lo closely wound whorls are separated by a tortuous, linear suture; the cystophic nuclear whorls are very small, protruding at the mucronic apex. 542178, was collected in person on August 2, 1944, in and under drift (mainly rotting coconut leaves) on the mangrove swamp side of the sandbar near the mouth of the Rio Marina, Isla de San Jose, Archipielago de.
This species had previously been found under fallen leaves at the inner or landward edge of this mangrove swamp on the east side of the island and of another smaller mangrove swamp on the west side.
36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I06 Genus MELAMPUS Montfort, 1810
The National Museum collections include numerous specimens from the Pacific of Salvador (Biolley) (U.S.N.M. No. 163063), the Republic of Panama, Cocos and Galapagos Islands, and Tumaco. This species' optimum habitat on San Jose Island appears to be in the decaying wood of logs and stumps at about the high tide line. They were seen in greatest abundance on San Jose in a small mangrove swamp on the west side of the island, in rotting logs subject to partial flooding at high tides.
They were found burrowing in the rotten "wooden floor" in almost every gallery or crevice in more. The variation in size is very great in this species, as is the degree of surface sculpture of the body whorl.
38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I06
Only one specimen of this species was found in a small stream on the southeastern part of San Jose Island. Shell small, elliptic, about three-quarters as long, low, about one-fourth as high as long, pale pink, thin, transparent. The anterior and posterior slopes are at the same angle, the anterior one is rounded into a blunt parietal curve, the posterior one is distinctly rectilinear.
The apex is located in the posterior third of the length and approximately one third of the width from the right margin. The species is quite widespread on this island, being also found in the drainage systems of Rio Mata Puerco and Rio Marina. It is the only fresh-water snail, except the Pomacea, which is not confined to a narrow zone above tidal waters, but occurs in the middle and upper reaches of streams, wherever the habitat is suitable.
40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I06
STYLOMMATOPHORA
Its increased occurrence in secondary jungle or scrub areas on San Josepoint due to possible accidental introduction to the island.
42 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1^6 Family ENDODONTIDAE
In the series taken on San Jose Island, there was considerable variation in the height of the spire. This large wood snail is easily distinguished by its size and prominent zigzag color pattern. Dead and bleached shells can be found on the jungle floor at any time of the year, but collecting live individuals is much more difficult on San Jose Island.
At the beginning of the rainy season (April and May) they contain young with shells of 2 whorls, ready to hatch. When the rains begin in April and May, they hatch and the young begin their tree life. Semi-adult young can be found only on the lower part of tree trunks or on the lower leaves of trees in mid-summer (July and August).
This small disc-shaped species, neatly marked with brownish, spiral stripes of color, was found in areas of the virgin jungle on San Jose Island, but nowhere in abundance. Perhaps the presence of feral pigs on the island makes life dangerous for these snails that live in the thin layer of leaf mold or under fallen tree trunks.
PELECYPODA
NO. 6 MOLLUSKS OF SAN JOSE ISLAND MORRISON 45 Family CYRENOIDIDAE
46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I06 and obviously all species examined by Baker possess only the anal
NO. 6 MOLLUSKS OF SAN JOSE ISLAND MORRISON 47
I06a low but well-defined posterior ridge ending in mid-subangular- a low but well-defined posterior ridge ending in mid-subangular posterior region. Right valve with a small cardinal tooth immediately below the umbo, and in front of the well-defined resial pit on the ventral face of the hinge; left valve with a small, broad, apparently tripartite chondrophore on its dorsal face. Moderate muscle signs; the pallial line is simple, the pallial sinus is represented by an expansion of the pallial scar.
This species can be distinguished by the extreme inflation of adults and the barely protruding umbilical cords. With the extreme inflation of the inflata, this island species has the prominence of the bill greatly reduced to produce an apparently cylindrical shape.
EXPLANATION OF PLATES
