Cotylogaster oceidentalis n. sp. 599 



in length thc transverse diameter of the worni. This series is com- 

 pletely surrounded by a Single margiual row of rounded or elliptical 

 depressions varyiug in number froni 100 to 110. 



The acetabula of the marginal row show uo regularity of arrange- 

 ment with respect to the grooves of the median series. 



Marginal organs are present corresponding in position with those 

 of Aspidogaster, Cotylaspis and Cotylogaster michaelis. Their striic- 

 ture will be described later. 



The sexual aperture is median ventral a short distance in front 

 of the anterior margin of the ventral shield when the aninial is fuUy 

 extended (Fig. 2). When the anterior portion is retracted the gono- 

 pore is carried backward so as to open into the sulcus surrounding 

 the base of the retratile neck (Fig. 7). 



A Cluster of deeply staining cells is present in the tissue at the 

 base of each of the marginal depression of the ventral sucker. They 

 are doubtless glandulär in function and correspond with the cutaneous 

 glands described as occurriug in corresponding positions in several 

 other members of the family. 



At the junction of the neck with the body the musculature is 

 refllected inward and backward to form a muscular tube withiü the 

 parenchyma. This lies near the dorsal side separated from the body- 

 wall by only a thin layer of tissue and extends backward to about 

 the region of dorsal flexure. It is composed of an outer coat of 

 longitudinal iibres, a middle coat of oblique fibres and a few inner 

 circular fibres, finer and less numerous than those of the other two 

 sets. Some of the muscle fibres forming the dorsal side of the tube 

 continue backward across the base of the dorsal cone and are 

 attached at the posterior end in the vicinity of the excretory pore. 

 The tube is larger at its anterior end and there occupies the greater 

 part of the body space but gradually diminishes in size posteriorly 

 (Figs. 7, 9 and 10). Within it are contained the intestine, the longi- 

 tudinal excretory tubules, and the terminal portions of the oviduct 

 and vas deferens. The other prominent organs, ovary, shell-gland, 

 testes, vitellaria and uterus are contained in the space between the 

 walls of this tube and the ventral and lateral body walls. 



As in other Aspidohothridae the digestive tract consists of pre- 

 pharynx, pharyux and simple unforked intestine. The prepharynx 

 extends this the centre of the neck from the mouth back to the 

 Pharynx, a distance varying in the three specimens measured, from 

 0.823 — 1.48 mm. The average of the three cases is 1.1 mm. Its 



