30 DESCRIPTIONS OF FOUR DISTOMES. 



is an elongated organ that occupies three-fourths of the space within the cirrus-sac. 

 The cirrus is short and weak. 



The ovary is a small ovoid body 0.16 millimetre in length that lies partly behind 

 the acetabulum and partly dorsal to it. It is just to the right of the median line and 

 is dorsal in position. The oviduct is a short tube which proceeds towards the me- 

 dian line through the shell-gland to the ootyp. The shell-gland lies next to the left 

 side of the ovary and in contact with the dorsal body-wall. It is about half the size 

 of the ovary. The yolk-glands consist of about twenty-five glandular bodies on 

 each side. They extend from the anterior end of the testes to the anterior end of 

 the acetabulum. Their position in the body is ventral and between the intestinal 

 caeca and the ventral body-wall. Three or four yolk-ducts leave the yolk-glands 

 on each side and proceed to a common point posterior to the ovary in the dorsal 

 portion of the body, where they meet to form the transverse yolk-ducts. These 

 ducts meet in the median line and form a short median yolk-duct which proceeds 

 to the ootyp. Laurer's canal arises in the ootyp and extends through the shell- 

 gland to the external pore a little to the right of the median line. The uterus consists 

 of a descending and an ascending limb, both of which have a serpentine course. 

 The descending limb proceeds from the ootyp between the testes to the hinder end 

 of the body; the ascending limb, which is much the larger of the two, proceeds 

 anteriorly along the median line, and on the left side of the cirrus-sac to the genital 

 pore. The terminal portion of the uterus forms a metraterm. The egg measures 

 0.035 millimetre by 0.02 millimetre. 



The following is a specific diagnosis of Renifer elongatus: Small, elongated 

 semi-cylindrical worms whose length is 3 millimetres and breadth 0.68 millimetre. 

 The oral sucker is subterminal and 0.33 millimetre in diameter. The acetabulum is 

 sessile and 0.36 millimetre in diameter. Body covered with minute spines. The 

 pharynx is of moderate size; the oesophagus is very small; the intestinal caeca extend 

 beyond the testes into the beginning of the posterior third of the body. The excre- 

 tory vesicle is very long and voluminous, Y-shaped, and with a long median por- 

 tion, and long crura. The testes are two, situated side by side, in the middle of the 

 body, behind the acetabulum and the ovary. The ovary lies immediately behind 

 the acetabulum. The yolk-glands are lateral, between the testes and anterior end 

 of the acetabulum. A Laurer's canal is present, but a receptaculum seminis is 

 wanting. The genital pore, nearly median, lies near the pharynx. The eggs meas- 

 ure 0.035 millimetre by 0.02 millimetre. Parasitic in the mouth of Heterodon 

 platyrhinus. 



