1913-] T. S0UTHWEI.1. : Parasites from Fish. 89 



fish. Such cysts have been obtained from Hilsa caught at 

 Monghyr, Buxar, Calcutta and Diamond Harbour. The cysts are 

 usually tadpole-shaped, but a few are strap-shaped. They vary 

 extensively both in size and shape. The strap- shaped examples 

 measured on an average 20 mm. long and 3 mm. broad. The 

 tadpole-shaped cysts measured on an average 30 mm. long. The 

 " head " of the cyst measured 3 mm. by 3 mm. and the rest of the 

 cysts are 12 mm. broad. The larva itself is contained in the 

 "head" of the cyst. This species appears to have a very wide 

 distribution and was first described by Linton, who obtained it 

 from a sting ray {Trygoti centnira) in tropical America. The 

 genus was founded by Diesing, Southwell also recorded it from 

 Ceylon (17) as under : — 



'' I have no hesitation in referring to this species a number 

 " of larval forms obtained from the intestines of Cyhiiim guttatum 

 '' and Chorenemus lysan. The head of the larva is squarish in 

 '' front view, with a bothrium at each corner. The bothridia are 

 " oval or cup-shaped. The larva agrees in every detail with 

 "Linton's figure of this species, save that in our types the exit 

 *' of the proboscides were closed. The proboscis sacs were marked 

 ' ' with fine criss-cross lines only visible under a high power. 



" Habitat I. The mesenteries of Chorenemus lysan. 



*■' February 25th, 191 1 ; 45 specimens. 



'' These larvae were enclosed in tadpole-shaped cysts. The 

 *' cysts measuring on an average 25 mm. by 2"5 mm. The larva 

 " was contained in the head part of the C3'st which, in preserved 

 " specimens, was of a yellow colour. 



The rest of the cyst was white, membranous and trans- 

 " parent. The larvae measured 2 mm. by "5 mm. 



'' II. The mesenteries of Cyhium guttatum. 

 " November 27th, 1910. 

 " Fifty- five specimens ; the same as the preceding. I believe 

 " these specimens to be the same as those described by Shipley 

 " and Hornell from Cyhium guttatum in Part V of the Ceylon 

 " Pearl Oyster Reports, plate iii, fig. 43. It is interesting to 

 " note that Linton states that he has met with encysted forms 

 " similar to this {Syndesmobothrium filicolle) in various species of 

 " Teleostei, such as Pomatomus saltatrix, Cyhium regale, etc. 

 '' He described one from Spanish Mackerel [Cyhium regale) in 

 " the ' American Naturalist ' for February 1887, under the name 

 '' of Tetrarhynchobothrium. 



'' The occurrence of this larva in these Teleosts raises the 

 question as to the position of this stage in the life-history of 

 " the parasite. On the whole I feel confident, and I have every 

 '' reason to believe, that the larvae normally inhabit the tissues 

 " of either crabs or molluscs, and have their adult stage in some 

 " Elasmobranch. The presence of the larvae in these Teleosts is 

 due to their feeding on crabs or molluscs, but the larva does 



