Cotylogaster occidentalis n. sp. f)(j7 



The vitellary glaiul is a Single continuous cord of tissue extend- 

 irig along eacli side of the body aud arching across tlie anterior end 

 just in front of the shell ghind (Fig. 15). Its ends are thicker than 

 the anterior arched portion and reach backward to about opposite the 

 end of the intestine. The unpaired duct arises upon the left side and 

 extends forward to join the oviduct just before the latter enters the 

 shall gland. I have seen no indication of a corresponding duct upon 

 the right side. Macraspis is the only other Aspidobothrid in which 

 the vitellaria have been found in the form of continuous bands of 

 tissue (Jägerskiöld '99); but in that form the connecting anterior 

 arched part is not mentioned and paired ducts are present. All others 

 Aspidobothrids so far as knowu have the vitellaria in the form of 

 separate rounded follicles arranged in a row along each side. The 

 condition in Stichocotyle is not known but it may not improbably be 

 found to resemble Macraspis and Cotylogaster occidentalis in this 

 respect. 



The festes are two in number, elliptical in outline and placed 

 one obliquely behind the other in the middle region of the body. In 

 all of the specimens (3) whose internal structure I have studied care- 

 fully the anterior testis is on the right side or (in one case) median 

 vvhile the posterior is on the left side. They are a little larger than 

 the ovary (500 — 550 X 250 — 275 i-i) and in my specimens are tilled 

 with cells showing various stages in the process of spermatogenesis. 

 The ducts leading from the testes (vasa efferentia) arise frora their 

 anterior ends but I have been unable to trace them to their point of 

 Union to form the vas deferens, The latter organ extends forward 

 thro' the inner muscular tube ventral to the intestine and upon the 

 right side of the uterus. The terminal portion of the vas deferens 

 reaching nearly half way back to the posterior end of the inner 

 muscular tube is enlarged and quite irregulär in outline and is sur- 

 rounded by a thick sheath of elongated gland cells (Figs. 7 and 15). 

 The lumen I have found occupied by masses of sperm and ova, the 

 latter probably drawn backward from the opeuing of the uterus by 

 some contraction of the body. The vas deferens and terminal portion 

 of the uterus unite just before opening to the exterior so that they 

 have a short terminal portion (genital atrium) in common. A penis is 

 lacking and I can oflfer no observations to show whether or not cross 

 fertilization occurs. 



The eggs in the oviduct before the beginning of cleavage are 

 spherical in form and measure about 26 f.i in diameter. The shell of 



Zool. Jahrb. XV. Abth. f. Syst. /J.Q 



