AMPHTSTOMA — ECHINOSTOMA. 39 



stance that the larvae or cercarias of another species [AmpMstoma 

 subclavatum) which, in the adult condition, dwells in frogs and 

 newts, have been found both by Filippi of Turin and Pagen- 

 stecher of Heidelberg, on the surface of the body of various species 

 of Planorbis ; it would seem also, that Van Beneden has found 

 them in different species of Gyclas. If this be correct, it becomes 

 quite clear that when deer, sheep, or cattle resort to ponds and 

 running streams to quench their thirst, they necessarily run the 

 risk of infecting themselves with these larvae ; and in this way they 

 are probably transferred to the paunch or rumen, where, becoming 

 attached to the internal lining membrane of the organ, they com- 

 plete their final stage of development. 



FjcMnostoma. — In this genus — or sub-genus, as originally 

 established by Dujardin — ^the oral sucker is surrounded by a circle 

 of little spines, or it occupies the centre of a disk which is cleft at 

 the ventral or anterior aspect. In the latter case the disk is either 

 bordered both laterally and above by spines, or there are two large, 

 lobed appendages,, whose margins are furnished with spines. In 

 other respects this genus very nearly corresponds with the typical 

 distomes, but the simple digestive tube bifurcates immediately 

 below the oesophageal bulb. As an illustration, I select the Echi- 

 nostoma hispidim,, which species Dujardin — being misled by 

 OrepHn's erroneous description — omitted to place in this genus, 

 although he had previously entertained a very strong suspicion 

 that it was a true echinostome. The specimen here drawn (Fig. 

 13) was taken by me from the spiral intestine of a sturgeon (1855), 

 in which fish it occurs very abundantly. It will be noticed that 

 there are two rows of large spines surrounding the cephahc disk, 

 the latter structure being incomplete at the ventral margin (which 

 is here turned away from the observer). The relative disparity 

 of the two rows of cephalic spines are better seen in more highly 

 magnified figures of these organs. The integumentary spines 

 clothing the general surface of the body vary considerably in 

 character, according to their position. Those situated at the 



