170 DR. J. MUEIE ON THE FORM AND STRUCTURE OF THE MANATEE. 



amazingly, foi-ming, as Owen has justly said of the same structure in Halicore, a 

 powerful sphincter " to defend the cardia against the pressure of the contents of the 

 stomach." This latter organ, indeed, is almost gizzard-like as respects its strength, of 

 which more hereafter. The oesophageal tube in the older female measured 10 inches 

 long from the posterior border of the inferior constrictor to the gastric extremity. Its 

 mucous membrane has quite a Cetacean aspect, there being some half a dozen longi- 

 tudinal furrows, and as many flattened ridges throughout its course. There are besides 

 innumerable very minute rugae disposed in wavy tx'ansverse striae, giving a kind of velvety 

 appearance to the ridged portions of the tunic when in the contracted condition. The 

 inner epithelial lining, as Steller also has noted in Rhytina, is pale-coloured and slightly 

 corneous in texture. I did not observe in Manatus any of those deep glandular pits or 

 crypts in the mucous lining which I have found scattered here and there in the oeso- 

 phagus of Physalus and Globiocephalus. 



Before reaching me, each Manatee had the stomach cut open and the contents 

 removed. Consequently this very muscular organ had shrunk considerably, and on 

 cursory inspection exhibited any thing but the enormous relative; proportion assigned 

 to this viscus in its congener the Great Northern Manatee. To Steller's surprise, four 

 stout men with difficulty dragged out the stomach of the latter animal examined by 

 him. The entire length of its carcass, however, was 24 feet 8 inches ; and the stomach, 

 full of fucus, measured 6 feet long by 5 feet across. But he further notes in the table 

 of dimensions, " Ventriculus latus sen longus potius " 44 inches. I suppose, therefore, 

 that this diminished capacity applies to the empty and contracted stomach, and to that 

 portion which corresponds to the so-called cardiac cavity of the Dugong and Southern 

 Manatee. If so, the cavity in question in the Rhytina has its long diameter in propor- 

 tion to the length of the body as 149 is to 1000, or rather more than \. In the male 

 Dugong, 6 feet 10^ inches long, dissected by Professor Owen in 1838, the first or 

 cardiac cavity was 9 inches in greatest diameter, equivalent, therefore, to one ninth 

 the animal's length. Taking the same portion of the contracted viscus in the female 

 Manatee as about four inches, this gives but one sixteenth as its proportion scale. 



Of the compound stomach and bifid caecum Daubenton's, Homes, and Vrolik's 

 original figures are suggestive, though not quite in accordance with my inspection ; nor 

 have they shown the interior arrangement of the parts [vide sections, PI. XXllL), which 

 are as remarkable as the exterior configuration. The first cavity is the most capacious, 

 and not unlike the human stomach in shape. Immediately to the left of the oesophageal 

 entrance, and bulging upwards to the side and partly behind the gullet, there is a pro- 

 tuberant cul de sac lined interiorly by corrugate mucous rugae. Beneath this is the 

 constricted orifice of the cardiac gland. From here, the narrowest part, the first 

 stomach widens to its middle, beyond the bend narrowing by degrees to the distal end, 

 which is guarded by a sphincter-like narrow passage communicating with the fourth 

 digestive compartment about its upper third. The inner tunic is composed of a pale- 



