388 GARRISON. 



Alimentary tracts. — The oral sucker is terminal or slightly ventro- 

 subterminal, the greater development of its dorsal side giving the oral 

 opening a more or less marked inclination toward the ventral surface. 

 It measures from 130 to 200 /* transversely and dorso-ventrally by from 

 75 to 130 fx antero-posteriorly (about one-third the size of acetabulum). 

 From the oral sucker to the pharynx extends a short, rather broad pre- 

 pliaryn.v which in some specimens appears almost obliterated bv the close 

 approximation of these two organs, while in others it is considerably 

 extended, its length in different specimens varying from 10 to 63 p. 

 The pharynx is globular and measures from 150 to 190 /a in diameter. 

 The cesophagus is very short (50 to 100 /*), its bifurcation occurring just 

 anterior to the plane of the genital pores. The thin walled intestinal 

 caca pass rather sharply outward toward the lateral margins and then 

 follow these margins rather closely to near the posterior extremity of the 

 body, one easeuin sometimes reaching a slightly more posterior position 

 than the other. Before they reach the equator of the body the ceeca 

 become bounded laterally, and also to some extent ventrally and dorsally, 

 by the vitellogen glands. 



Excretory tracts. — In the posterior fifth of the body the excretory tract 

 is single and dilated into a cavity of considerable size with irregular, 

 ill-defined walls ("excretory bladder"). On reaching the posterior border 

 of the caudal testicle the tract divides into two lateral branches which 

 pass cephalad between the median and lateral fields above noted to a 

 position dorsad of the acetabulum where approaching the median line, 

 they are separated by only a thin septum. (In some sections the two 

 tracts appear actually to join anteriorly.) 



Male organs. — The testicles occupy the posterior part of the median 

 field of the middle portion of the body and lie one immediately and 

 directly behind the other in the median line. They are bounded pos- 

 teriorly and laterally by the excretory tracts. Each testicle is more or 

 less distinctly divided by a transverse circular constriction into an 

 anterior and posterior lobe. In some specimens, this constriction is very 

 slight and the testicle appears almost oval, while in others it is well 

 marked and there may be even slight indentations at other parts of the 

 surface, marking off four or five poorly defined lobules. From each 

 tetsicle the vas deferens passes forward through the lateral (marginal) 

 fields to a position dorsad of the acetabulum where the two enter the 

 posterior end of the cirrus pouch. The cirrus pouch measures from 560 

 to 608 fi in length by from S40 to 280 jx in breadth and is situated dorso- 

 anterior of the acetabulum, with its axis directed forward and ventrad, 

 and also slightly to the left side. Posteriorly it contains a large vesicula 

 seminalis which receives the vasa deferentia and which as seen in different 

 specimens appears to be capable of considerable distention. Within the 



