The stomachs of the Zoophagous Cetaceans are very complicated : the number of these in various species, and in different individuals of the same species, has been variously given by different authors. Some have stated the number in the common Dolphin and Porpease at three, others at four, others at five, others at six. F. Cuvier con siders it as certain that these numerical differences proceed simply from the manner in which the organ is viewed. Professor Owen was unable to distinguish more than four compartments in the stomach of the Porpesse. In general the spouting whales have no mecum ; but a trace of it has been found in the Platanist, and it actually exists in the Piked and Whalebone Whales.
John Hunter pointed out the considerable degree of uniformity present in the liver of this tribe, observing that in shape it resembles that of man, but that it is not so thick at the base nor so sharp at the lower edge, and probably not so firm in the texture. The right lobe is the largest and thickest. Them is no gall-bladder. The same distinguished comparative anatomist describes the pancreas as a very long flat body, having its left end attached to tho right side of the first cavity of the stomach : it passes, he adds, across the spine at the foot of the mesentery, and near to the pylorus joins the hollow curve of the duodenum, along which it is continued and adheres to the intestine, its duct entering that of the liver near the termination of the gut. In the Piked Whale the spleen is single and small ; in the Porpesse it is subdivided into several distinct portions.
There is an interesting, series of preparations illustrative of the anatomy of the Cetacea in the museum of the College of Surgeons, and well deserving the attention of the student of comparative ana tomy. One of these preparations, No. 323, is a perpendicular section of several plates of whalebone, with the intermediate substance and vascular nidus, from the upper jaw of a young specimen of the Great Whale (Baltena mysticetus, Linn.). The disposition and relative pro portions of the plates of whalebone are hero shown; from which dispo sition it results, that only the fringed extremity of the whalebone plates arc visible from the inside of the mouth of the whale ; the whole concavity of the palate appearing to be beset with coarse rigid hairs or bristles, which explains the passage in Aristotle (' Hist Anim.' iii. 12), who, speaking of the Great Whale Owen-hares, or, as Bekker
roads it, 6 A.017"6 '61700, says, Mysticete has no teeth in its mouth, but hairs like hog's bristles." Circulating System.—Phytophagous Cetaceans.—The three Dugongs dissected by Professor Owen presented the same remarkable extent of separation of the two ventricles of the heart described by Sir Everard Home and Sir Stamford Raffles in the individuals examined by them, and observed by Riippell in the Dugong of the Red Sea (Medicare Tabernaculi). Daubenton appears to be the first who noticed this condition of the heart, in his dissection of the foetus of the Mana tee. Steller also described it in the genus which bears his name ; but in that animal the apical cleft of the heart extended upwards only one-third of the way towards the base, whereas in the Dugong it reaches half-way towards the base.
Professor Owen found the foramen ovale completely closed, and the ductus arteriosus reduced to a thick ligamentous cord, permeable for a short distance by an eye-probe from the aorta, where a crescentic slit still represented the original communication. He states that in the smoothness and evenness of their exterior and their general form the auricles of the Dugong resemble those of the Turtle (Chelan), and that the appendix can hardly be said to exist in either. The right auricle is larger than the left. The primary branches from the arches of the aorta correspond in each specimen with Sir Everard Home's figure and description. There was only one superior cava, not two, as in the Elephant ; and the pulmonary veins terminated in the left auricle by a common trunk an inch in length.
As no mention had been made in the anatomical descriptions of the Herbivorous Cetaceans by Daubenton, Steller, Curler, Raffles, and Home, respecting the existence or otherwise of the extraordinary intercostal and intervertebral arterial plexuses present in the true Cetacea, Professor Owen carefully followed out this part of the dis section, but could detect no trace of this very striking modification. Here again, he observes, in enunciating a general anatomical propo sition regarding Cuvier's Cetacea, the Herbivorous species must be exceptionally cited apart.
Zoophagous Cetaceans.—Professor Owen remarks that the Carni vorous Cetaceans do not participate in the structure of the heart above described with the Herbivorous section.