100 Records of the Indian Museum. [Voi,. IX, 



black shiny substance having the consistency of wet clay. It is 

 possible that this substance represents decomposed blood, the 

 exudation of blood into the air-bladder being caused by the suck- 

 ing action of the parasite. Unfortunately a sample was not 

 kept for examination. The parasites lay embedded in this mass 

 and measured i6 mm. long and 5*5 mm. broad. In shape they 

 were cylindrical. The oral sucker is terminal and subventral. 

 The ventral sucker is situated 3'5 mm. from the anterior extremity. 

 Both suckers have a diameter of 'S mm., and are but feebly 

 developed. The most remarkable feature of this parasite is the 

 almost entire absence of muscles from the body- wall, the various 

 organs being encased in an exceedingly thin diaphanous transpa- 

 rent cuticle. This circumstance is to be correlated with the habits 

 of the parasite, living as it does in a medium where movement 

 is well nigh impossible. The mouth is situated at the base of the 

 oral sucker. This leads directly into a muscular pharynx. The 

 oesophagus is very short. The two rami of the intestine are large 

 sinuous tubes having a diameter of i*i mm. and being usually 

 filled with a dark brown material apparently derived from the 

 medium in which they live. Both rami of the intestine run to 

 the extreme posterior end, where they terminate blindly. 



As only a very few specimens of the parasite were obtained^ 

 it was found impossible to satisfactorily make out, with certainty, 

 the precise details of the reproductive system. I am therefore 

 not certain that the following description is absolutely correct 

 in ever}' detail. 



The genital pore is minute and is situated ventrally, imme- 

 diately posterior to the oral sucker. 



The testes are a pair of very large, sinuous, cylindrical bodies 

 situated one on each side, and extending to a point about 6 mm. 

 from the posterior extremity. Anteriorly, each gives off a vas 

 deferens, and these unite in the middle line. The cirrus is bent 

 upon itself. The main mass of the vitteline glands is aggregated 

 over a loop of the intestine, one mass on each side, immediately 

 behind the termination of the testes. The main ducts run 

 transversely, towards the median line, and open at the junction 

 of the ovary and shell gland. These latter organs are situated 

 close together, in the middle line, about 5 mm. from the posterior 

 extremity, the shell gland being posterior to the ovary. The 

 uterus is a coiled tube. For the first part of its length it lies 

 posterior to the ovary, and then runs forward, sinuously, in the 

 middle line (anterior to the ovary) to the genital pore. 



The excretor}^ pore is terminal, but no details of this system 

 could be made out. 



*' Distomum " sp. ? 



(PI. x, fig. 19.) 



Four specimens of an immature species of " Distomum " were 

 obtained from the intestine of Ophiocephalus striaius, the same 



