Echinostdiiinin yarzettae u. sp. 543 



ventral sucker a quite large yellow area indicates tlic positioii of 

 tlie Uterus filled vvitli eggs. 



The skiii as seeu in section exliibits a very dense liig-lily relrac- 

 tive superficial layer of liomogeneous appearance wliile in tlie tliicker 

 underlying layer there is a vertical striatiou ^\liicli witli some g-ranules 

 and vacuoles g-ives tlie cuticle a considerable opaeity. The paren- 

 chyma which supports the ergans is eomposed largely of stellate or 

 branching cells with vesicular nuclei. The body musculature has 

 the usual arrangenient. specially powerful doi-soventral and oblique 

 bands being found in the anterior expansion \Yliere some fibrils run 

 to each marginal spicule. 



The anterior or mouth sucker is a very weak structure, but it 

 is eomposed of all the muscular layers usually found there — it communi- 

 cates directly with the sliort prepharynx which is lined with cuticle 

 and which enters the elliptical muscular pharynx. This structure 

 which measures .24 X -34 mm gives directly into the relatively short 

 Oesophagus which is surrounded by numerous glandlike cells possibly 

 serving to secrete some dig-estive material. This in turn divides 

 near the front of the acetabulum to give off the simple lateral in- 

 testinal coeca which run to the posterior extremity of the bod}'. 

 The coeca appear to possess a circular muscular coat only, with a 

 smooth lining of rather high epithelial cells. In this instance they 

 are entirely empty. 



The ventral sucker shows microscopically the usual cuticular 

 liniiig-. radial and circular niuscle fibres and the large deeply staining 

 cells among these fibres which have been so frequently described. 

 Tiie sucker seems to be almost surrounded by a curious space or 

 sac in the body parenchyma Avhich evidently constitutes part of the 

 excretory System and will be referred to later. 



This excretory System is complicated and peculiar. At the 

 posterior extremity in the median line there is a large tliin walled 

 sac lined by a flattened epithelium which opens as stated above by 

 means of a cuticle lined canal at a point on the dorsal surface just 

 in front of the posterior end of the body. Anteriorly it is conti- 

 nuous with widely ramifyiug sacs which penetrate every part of the 

 body even pushing into the tliin lateral portions between the lobules 

 of the vitellarium and the muscle bundles to approach the skin. 

 They are also seen in the most anterior part of the body, in the 

 head disc iutercalated in the meslies of the tissue, so that the whole 

 body appears as a sponge-like mass. They are lined by a transparent 



36* 



