1913.] T. Southwell : Parasites from Fish. Sy 



which are pureh^ freshwater forms is not more than 30, or approx- 

 imately I '5 per cent. 



Specimens of the parasites described in this paper have been 

 deposited in the Indian Museum. 



Ophryocotyle bengalcnsis, sp, nov. 



(PI. vii, figs. 1—3.) 



Over sixty specimens of this worm were obtained from the 

 intestine of Ophiocephalus striatus, and a few were also obtained 

 from the intestine of Labeo rohita. Both fish were caught at 

 Berhampur Court, Bengal, in a freshwater tank. This genus of 

 tapeworm usually occurs in birds, and considerable interest attaches 

 to the presence of these adult forms in Teleosts. The average 

 length of the worms was 7-5 mm. Greatest breadth (at posterior 

 end) -8 mm. These latter segments were from 4 to 5 times broader 

 than long. The head consists of four cup-shaped suckers, directed 

 slightly forward. Anteriorly the head terminates in an umbrella- 

 shaped protrusible rostral disc whose circumference is armed with 

 a large number of hooks arrranged in two rows. The exact 

 number could not be determined, as, in removing the parasites 

 from the intestine of the fish, many of the hooks had been torn 

 away. The exact number counted in three specimens is given 

 in the following table ; — 



(i). One row of twenty-five hooks 

 (ii). Two rows with a total of fifty-three hooks, 

 (iii). Two rows with a total of fifty- two hooks. 



The hooks appear to be all similar. They have broad bases 

 and are sharply recurved in profile. Viewed end on they appear 

 elongated (plate vii, fig. 3). 



The suckers are armed with exceedingly minute spines which 

 appear to be limited to their anterior borders. The head measures 

 about '5 mm. broad. The neck is fairly long, measuring 27 mm. 

 Dots of black pigment are scattered about over the whole worm. 

 The first proglottides are exceedingl}'' shallow, and all proglottides 

 are broader than long. The lateral margins are wrinkled in such 

 a way that in young specimens the true strobilization can only 

 be determined under a lens. The genital apertures are lateral 

 and are almost all on one side. 



The uterus appears to be made up of a number of rounded 

 egg capsules scattered about the proglottid. 



Habitat. — The intestines of Laheo rohita and Ophiocephalus 

 striatus. Berhampur Court, Bengal, June 1912. About sixty 

 specimens. 



xlmongst the worms just described were two large specimens 

 measuring 27 mm. and 22 mm. respectively. They differ from the 

 smaller forms only in having the neck very much shorter and in 

 being much larger. Two rows of about 50 hooks were counted 

 round the circumference of the rostral disc. 



