80 DUEPANOMENIA VAMPYRELLA. 



extensive anterior coecinn. On this sack a number of short outgrowths are 

 developed chiefly on the dorsal side. A short distance behind the front end of 

 the gonad gut jiouches appear arranged with great regularity, and from this 

 point on digestive cells attain their fully developed condition. In the region 

 of the pericardium the sacculations vanish, the canal narrows rapidly and the 

 liver cells are replaced by low columnar cells thrown up into longitudinal ridges 

 extending to the opening into the cloacal chamber. 



In this specimen the pericardial cavity is relatively large (Plate 6, fig. 3), 

 and the lieart it contains is considerably distended with blood, rendering it 

 possible to some extent to determine the coiu'se of the circulation. The blood 

 returning from the gills, and another smaller jiortion that appears to come 

 directly from the hinder portions of the body, pours into a well-defined auricle 

 situated at the hinder end of the pericardial cavity beneath the ventricle. Its 

 walls are only slightly less muscular than those of the ventricle, and owing 

 possibly to muscular contractions, are developed into several pouches that do 

 not have the appearance of blood glands. From the auricle the blood passes 

 into the ventricle through a comparatively large opening guarded by a well- 

 developed muscular flaji jirobalily functioning as a valve. 



From the front end of the ventricle a clearly defined vessel arises, and 

 passing forward unites with the dorsal aorta. This latter vessel holds its usual 

 position between the l)ody wall and gonad, but it extends backward over the 

 dorsal side of the pericardium as far as the posterior end of the ventricle. Anteri- 

 orly the relations of the vessels in the gonad and of the aorta to the head cavity 

 are essentially as they are in P. haivaiiensis. This appears to be the case also 

 with the sinuses in other parts of the body, though using longitudinal .sections 

 through the somewhat twisted body, it is not possible without much labor, 

 to determine their connections accurately. 



With the jirotrusion of the jiharynx the brain has been carried some dis- 

 tance ventrally, Ijut luuler ordinai'y circumstances its position and the relations 

 of the nerves which it develops are probably not umisual. As Plate 7, fig. 4, 

 shows three pairs of nerves pass to the atrial wall as in other of the Neomeniina, 

 and are probably destined, here as there, to supply the cirri, anterior muscula- 

 ture, and hypodermal sense organs. So far as may be judged from sections, 

 the labio-buccal connectives originate some distance from the pedal and pallial, 

 and may be clearly seen to jiass down to ganglia situatetl on the sides of the 

 pharynx where it luiites with the buccal wall. From the hinder border of each 

 ganglion a fibre originates that may be the inferior or vcntial commissure, but 



