Some undescribed Trematodes. 407 



deep. It often exhibits a constriction at tlie middle of the body ; and 

 at the sides of the mouth-sucker a pair of lateral expansions is often 

 to be Seen. 



The suckers are nearly equal in size — about 0,275 mm, in sec- 

 tions, although the ventral one appeared to me rather the smaller, in 

 the living animal. It is situated near the middle of the anterior half 

 of the animal. 



The integument has a cuticle, and the longitudinal muscle fibres 

 are especially large. 



Mouth, pharynx, and lateral intestines are present, as usual; the 

 latter being especially long, reaching to the posterior end of the animal. 



The median, unpaired expulsion canal of the excretory System is 

 very long, extending from the posterior porus to the ovary, near the 

 ventral sucker, where it divides into lateral, anteriorly directed 

 branches. 



Of the reproductive System, the testes are conspicuous, near the 

 middle of the body, in the broadest part, just behind the constriction. 

 One is situated behind and to the right of the other. Narrow vasa 

 deferentia connect them with the penis, lying to the right of the ventral 

 sucker. A seminal vesicle lies in the base of the penis sack, and is 

 contiuued, as a ductus ejaculatorius, to the genital sinus, which opens 

 ventrally, immediately behind the forking of the intestine. 



A Single ovary lies behind and to the right of the ventral sucker, 

 The oviduct soon gives off a Laurer's canal which curves upwards 

 to open in the mid-dorsal line, above the posterior, inner edge of the 

 ovary. At an equal distauce beyond this again is the duct of the 

 yolk reservoir, from which latter proceed, sideways, the two transverse 

 vitelline ducts. Following the mouth of the yolk reservoir the oviduct 

 forms an ootyp with its shell gland, a receptaculum seminis uterinum, 

 and then the uterus which lies between the anterior testis and the 

 genital pore into which its distal end opens. 



Yolk glands are situated laterally from the intestinal caeca, in 

 the second half of the body^). 



6. Distonium angustum n, sp, 



The worm here referred to I found in the intestine of the Painted 



1) In outline this animal resembles the one figured and described 

 by A. Leakd, in: Quart. Journ. microsc. Sc, (N. S.) V. 2, 1862, pp. 168 

 — 170, under the name of D. constructum. Habitat and structure are, 

 however, different. 



