474 PARASITES OF ANIMALS 



important role. These parasites closely resemble the strongy- 

 loid Sclerostomata, but the absence of a true bursa seems to 

 justify their separation into a distinct family. In most of them 

 the body is truncated in front and much narrowed or drawn 

 out posteriorly. The head is broad and globular, and furnished 

 with a powerful muscular pharynx. The mouth is seldom 

 round ; it is often subterminal, opening by a transverse slit. 

 The tail of the male is recurved, and usually supplied with 

 membranous winged appendages ; sometimes there is a pre- 

 anal sucking disk. In the female the tail is simple, and more 

 or less sharply pointed. 



FIG. W.Cuctillanus forcolatus. Female. From the plaice (Platessa tulgar'u). Magnified. After Busk. 



The facts relating to the development of these parasites are 

 especially interesting as having afforded Leuckart and Fed- 

 schenko a clue to what obtains in the guinea-worm (Dracun- 

 culus). The Cucullanus of the perch (G. elegans) is a vivipa- 

 rous species. The embryos are supplied with little boring 

 teeth, or styles, which enable them to perforate the bodies of 

 entomostracous crustaceans. Having in a direct manner gained 

 access to the perivisceral cavity of Cyclops, they remain coiled 

 within the intermediate bearer until it has been pursued, 

 captured, and transferred to the stomach of the ultimate or 

 piscine host. Once liberated within the stomach of the fish the 

 young Cucullani soon acquire sexual maturity. 



The acanthocephalous Echinorhynchi are very abundant in 

 fishes. They also, like the Cucullani, require a change of 



