402 CETACEA. 



from the central thickened area, and sparsely scattered, minute villi and folds like 

 the bare spots of the chorion generally. The blood-vessels of the chorion branch 

 dichotomously and do not show any of the tortuosities which characterise the 

 chorion of the mare. A very few vessels, however, almost as fine as human hairs, 

 distributed over the allantoid portion of the amnion, are somewhat tortuous, but 

 in a moderate degree. I have traced these vessels into the arteries of the cord. 



One of the dorsal surface bare spots situated 8 inches to the right of tiie funis 

 is distinguished from all the other smooth spots of the chorion by bearing a 

 shortly pedunculated solitary corpuscle. This spot has a diameter of 0*25 inch. 

 The corpuscle does not occupy the centre of the spot, but is placed to its left side, 

 (Plate XXXIV, fig. 4). 



The membrana intermedia can be separated from the chorion and the amnion. 

 The attachment of the allantois to the membrana intermedia, and through it to 

 the chorion, differs from that of Flatanista in this respect, that the allantois 

 adheres more to the ventral and posterior surface of the chorion, whereas, in 

 the former genus, it is attached from the posterior towards the dorsal surface. It 

 differs also in form from that genus, the portion opposite the funis being pyramidal, 

 and the continuation on either side of it being narrower and more tubular than in 

 Flatanista, but in its linear extent it resembles the latter. 



The corpuscles of the amnion are very much larger than in P. gangetica, but 

 have much the same distribution. Each corpuscle is white at its base, and many 

 of them have short peduncles, while others appear to have fallen off, leaving their 

 peduncles. Some of these bodies on the cord, in its last 3 inches, have peduncles 

 an inch in length, but they do not exceed four to six in number, the majority being 

 sessile. A few corpuscles also occur on the amnion, where it is reflected off the 

 allantois, but close to the margin of the latter, to the right of the funis, and on 

 the ventral aspect of the sac. 



The allantois terminates 2 inches from the extremity of the right horn of the 

 chorion, and it extends about 2 inches beyond the bare spot corresponding to the 

 left Eallopian tube. It has thus a length of about 36 inches in the chorion con- 

 tracted by preservation in spirit. At 7 inches from the left pole it has a breadth of 

 3 inches between the two points where it is reflected off the chorion, while opposite 

 the funis the same interval has a breadth of about 7 inches. 



Microscopic structure of the chorion.— In the partially injected chorion, its 

 rough surface presents a villous vascular appearance somewhat resembling that of 

 Flatanista (Plate XXXVII, fig. 13), the villi, however, being shaggier and more un- 

 equal in size. In a vertical section of the chorion from the gravid horn of the uterus 

 of Orcella, not injected (fig. 14), the inequality of the villous tufts is apparent. 

 In some places they are bud-hke, low and closely set, at other spots a portion of the 

 membrane protrudes and throws forth long loops of arborescent vascular villi, thus 

 giving rise to deep unequal intervals and to a pseudo-cotyledonary character. The 

 chorionic villi are freely covered by squamous epithelium, though in some spots I 

 could observe a modified cylindrical kind. The basement membrane is of the usual 



