494 CETACEA. 



These recall to mind the moniliform vessel of O^^ca and the sac-like dilatations 

 of the arteries on the stomach of Orcella. In other instances the venous channels 

 send off a diverticulum or side chamber (fig. 7), which occasionally is connected by 

 a narrowed orifice with a subsidiary sac. 



In a partially transparent transverse section of the umbilical cord (PL XXXVI, 

 fig- 11) J the arrangement of the two main arteries and two veins is shown, and 

 besides, marginally and between the latter, a large vacuity, a probable remnant of 

 the urachus. Both arteries and veins have relatively thick and dense walls. The 

 urachus cavity is much thinner-walled, and interiorly I made out the remains 

 of minute and short papillae with an epithelial covering. Towards the peripheral 

 margin of the cord the gelatine of Wharton is loose-meshed, and traversed by narrow 

 ellipsoidal channels. Although these approach the superficial glandular bodies, they 

 nevertheless do not seem to have any connection with them. 



Foetus (PL XXXI, fi^. 1, and PL XXXII, fig. 4).— The mouth of the foetus 



was only partially closed, but its openness was probably a post-mortem result, 



as the palatal surface had a longitudinal mucous ridge corresponding to a deep 



groove in the middle of the flat prelingual surface. The outer aspect of both 



jaws was raised into well-marked vertical ridges, and increasing in size from 



behind forwards and terminating in marginal papillary eminences, through which 



the sharp teeth could be felt; and on the right side there were eighteen such 



columns more or less visible on both jaws, and sixteen on the upper and 



eighteen on the lower on the left side. The angles of the mouth and the 



blow-hole were filled with a consistent grumous substance which appeared to 



be cast and disintegrated epithelium, as a few broken nucleated epithelial cells 



could be detected in it under the microscope. The pectoral flippers were laid 



backwards against the sides of the body, and the free margin of the right was 



slightly folded on itseK. The dorsal fin was bent to the left side. The left caudal was 



folded inwards against the under surface of the right flipper, while its tip was bent 



over its own upper surface ; the tip only of the right caudal flipper being folded in 



a manner similar to its fellow. In the two foetuses which have come under my 



observation the bodies have been marked by corresponding folds. Among the most 



prominent of these is a deep fold which marks the position of the neck, occurring 



half-way between the angle of the mouth and the pectoral flipper. It is deepest on 



the ventral surface and extends up the side to nearly on a level with the eye. Two 



other somewhat similar folds occur, one before and the other behind the anus, but 



as they are due to the downward and forward bending of the caudal portion of the 



animal they disappear shortly after birth. On the dorsal surface there are four large 



folds which have been alike in both foetuses : a shallow transverse fold shortly 



behind the blow-hole and corresponding in position to the gular fold ; a second 



somewhat double fold stretching between the pectoral flippers ; and another occurring 



at a third of the distance between the latter structures and the tip of the dorsal 



flipper ; and a fourth half-way between the third fold and the dorsal fin. Behind 



the dorsal fin there are seven to eight short transverse folds across the rather sharp 



