This (Plate 1) shows that the dots are only a local thickening of the epidermis, apparently colorless in contrast to the surrounding surface. The dorsal edge of the stem is sharper or sharper than the ventral edge. There is a large variation in the intercondyloid portion of the basioccipital part, as it measures 8.5 mm in 240003.
Lateral aspect of the right side of the neombris skull, SHOWING PART OF THE RESPIRATORY SAC (arrow. This condition is most likely to be important in a study of the teeth of toothed whales).
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In 240864 there was a pair of these cervical ribs attached by syndesmosis or fragments of fibrous tissue to the ventral aspect of the transverse processes of the seventh vertebra of this series. Pre-skeletons contain a series of bone fragments consisting of small pieces of broken ribs, bony bones, and vertebral outgrowths. The center of the first six thoracic vertebrae and the seventh cervical has facets for the capitular attachment of the first seven cervical ribs.
4RT. 13 ANATOMY OF CHINESE FINLESS POBPOISE HOWEUL, 13
The length of the lumbar vertebrae varies from 25 to 29 percent of the total length of the vertebrae. The diapophyses of the first lumbar are suddenly much longer than the diapophyses of the last pectoral. In 239990 and 49544 the lumbar spines rise to the height of the caudad, but in the others they are all about the same.
Tail vertebrae. — There are 32 caudal vertebrae in one, 31 in three, and 29 in one of the specimens before me. In the only three cases where this could be accurately measured, the caudal series represents 42 to 46 percent of the vertebral length. The first seven have both capitular and tubercular attachments, the former being at the center of the vertebra immediately posterior to the tubercular articulation craniad.
The parts of the ribs commonly designated as costal cartilages in most mammals are completely calcified. In two of the specimens present there are sternal fenestrae (caused by the lack of ossification between the centra) similar to those illustrated by Allen in his Plate 3. There is very little variation in the scapula proper, but much, accounting for 100 per cent, in the width of the acromial process.
As illustrated, the central portion of the radius is almost twice as wide as that of the ulna.
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MYOLOGY
19 are features of the latter which are somewhat difficult to reconcile with the anatomy of the Cetacea as reported by others, and the descriptions are far from complete, while the anatomy of Balaenoptera^ it is a whalebone in many respects of. On the following pages these papers are usually referred to by the names of the generals involved - rarely by the authors. It should be mentioned that there is probably considerable individual variation of certain myological features.
Thus, direct comparison revealed a large difference in the size of the superficial masseter in the two dissected specimens, while the mastohumeral was small in the other, but was found to be significantly larger in It is practically absent on the side peduncle, fins and sides of the head. A remarkable feature of the musculature of this, and very likely all whales and dolphins, is the fact that in many areas the muscles are not attached directly to the bones, but to a solid membrane which more or less loosely embeds the bone.
Such a membrane covers most of the occipital region of the skull, especially around the exoccipitals, the entire scapula, ribs and parts of the vertebrae being thus covered. As in most if not all cetaceans, there is a tendinous raphe (although it sometimes appears to have been overlooked) extending caudodorsad from the caudal border of the flipper, and it is clearly discernible as such for at least 200 mm. Inserted into this raphe are muscle fibers with a slight cranial slope, running from both the dorsal and ventral regions.
On the anterior and central thorax the fibers can only be clearly distinguished if they are well ventraded in the direction of the flipper.
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AET. 13 ANATOMY OF CHINESE FINLESS PORPOISE HOWELL 21
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The origin is longer caudad than in the latter genus, which changes the inclination of the fibers. It arises from the temporal fossa and passes under the postorbital process of the frontal. Insertion is on the edge and adjacent lateral surface of the mandibular coronoid process.
The stout monogastricus, or rostral stomach of the more usual digastricus, originates from the lateral 30 mm. In Kogia the origin was only twice as long, relatively speaking, for it was from the entire basihyal instead of the terminal half. The slender and rather weak styloglossus originates from the approx. 20 mm long cranial margin of the stylohyal.
Hyoglossus originates from the most cranial part of the stylohyal and ceratohyal, with some fibers from the basihyal. Origin from the tissue of the ventral surface of the cranium of the pharynx of the hyoid system, and. It does not approach the medial line, but originates from the latero-cranial process of the sternum and inserts into the lateral part of the thyroid cartilage.
This muscle is apparently the same in Kogia, Balaenoptera, and Phocaena, though in the former genus Schulte states that the origin is also from the cartilage of the first rib.
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Murie says that in Glohiocephala this muscle extends from the transverse process of the atlas to well after the caudal part of the thorax, but this seems doubtful. Rather, the fibers arise just craniate of the vulva between the fasciculi of the lateral abdominal muscles. Insertion is on the caudal part of the sternum, and most likely from the adjacent costal cartilage.
Details of the origin of this muscle in Glohiocephala cannot be seen in the illustrations of this animal. The caudal border of the muscle is on a line running from about the twelfth thoracic vertebra to a point just in front of the vulva and. Ohliquus abdominis internus, with fibers running cranio-ventradally, arises from the deep dorsal fascia and several caudal ribs, including the sternal parts.
The insertion is made in the deep part of the rectus sheath and in the tissue around the urogenital openings. Judging from published descriptions, it appears that the muscular layers that make up the abdominal walls of Cetacea are somewhat heavier than usual. Owing to the condition of the specimens, the fibers of the original part cannot be followed in satisfactory detail.
However, it arises from bundles of several costae and the insertion is in the medio-caudal part of the humerus away from its middle.
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The underlying muscle mass could not be separated and the fibers apparently originate from both the spinous processes and most transverse processes of the vertebrae involved. The more ventral fibers originate from near the tubercles of the first four (?) ribs. When passing through the latero-craniad, the insertion takes place on the membrane over the edge of the exoccipital and also on the transverse process of the atlas.
The insertion is along the entire supraoccipital from practically the middorsal line to a point on the exoccipital caudad of the thezygomatic process of the squamosal. The origin is from the cranial border of the transverse processes of several or more cranial thoracic vertebrae. The former seem, on the whole, more complicated and specialized, as well as stronger, which may depend on the condition of the pig specimens.
They arise from the terminations and for a short distance on the dorsal surface of the transverse processes of the lumbo-caudal vertebrae, the muscle being only strongly tendinous towards the stalk. The intertransversarius inferioris throughout its length is a copy of the lumbo-caudal part of its superior neighbor, but it arises from the ventral parts of the terminations of the transverse processes. Postcostal hypaxial Tnusculature.— The hypaxialis of the lumbocaudal region is enormous, being even more massive in cross-section than the epaxial or supravertebral muscles.
The extent of this muscle is both over the entire lateral side of the scapula and.
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The fibers converge, the muscle becomes partially tendon-shaped and passes over the femoral head to insert into the craniolateral infraspinous fossa of the humerus. In Balaeiwpterathe the origin occupies the middle of the lateral aspect of the scapula and the insertion is more proximal. Teres' major originates from the scapular membrane along the axillary border of the scapula adjacent to the glenovertebral angle.
In Balaenoptera the origin is much more extensive and forms a considerable area above the more caudal part of the lateral side of the scapula. No muscle is attached to either the acromion or the coracoid process, and the triceps remnant is the only muscle that extends distad of the humerus. Despite a careful search, they found nothing that could be interpreted as the remains of any other fin muscle.
After removing the wrap from the forelimb, the fibrocartilage is seen to be in a definite position, suggested in Figure 12. Blow hole. - The blob hole was investigated by cutting thin horizontal sections from this part of the head. The rest of the passages and additional air bags seem to have a lot of individual variation.
In another specimen, a deeper respiratory sac was dissected, connected by a passage running caudally to the extreme lateral part of the exhalation foramen, and this was continuous in communication with an additional sac located caudal to the exhalation foramen.
40 PEECEEDINGS OP THE NATIONAL MUSEUM VOL. 70 difference in size between the right and left air passages was
It is interesting to note that on the anterior part of the acute border there is a well-developed row of papillae. No dissection of the pharynx was made, but the epiglottis was noted to be of the type illustrated for Glohiocephala. At two-thirds the distance to the bottom of this division, and hidden between two of the heavy folds, is a narrowed passage to the third division.
From this second section this section is absolutely undifferentiated and despite careful search it was only by dissecting from the third section that its existence could be demonstrated. The third section is double, and is somewhat V-shaped with smooth, rubbery lining, each part being about 44mm. The fourth division was similar in size and character to half of the third and was separated from the latter by another oval constriction, this being only 5 mm.
70 The postgastric part of the intestine was all of the same character, with a uniform width of about 10 mm. The alimentary canal was not only free of detectable intestinal parasites, but was completely empty, indicating that the animal had been seized for some time before it was killed.
LITERATURE
ART. 13 ANATOMY OF CHINESE FINLESS POKPOISE HOWELL, 43
