358 University of California Publications in Zoology. [Vol.6 



Gyrocotylt amphiptyches. Diesing ("Kevision der Myzhelmin- 



then," 1858) recognizes Amphiptyches as a distinct genus, plac- 

 ing it near Amphistomum under trematodes, in the place occupied 

 in his earlier paper (1855) by Gyrocotyle, then considered an 

 ectoparasite of Antilopt pygarga. He supposes Amphiptyches 

 to have a mouth, digestive tract and anus, in the face of Wag- 

 oner's (1852, p. 547) explicit statement to the contrary. He 

 gives as its habitat the gills and intestinal tract of Chimaera 

 monstrosa. His own genus, Gyrocotyle, he puts under the 

 Bdellidea near Malacobdella (Diesing, 1858, p. 492). He makes 

 certain changes in the generic description, the most important of 

 these being in the interpretation of the ventral canal opening 

 (proboscis of Spencer) ; in his description of 1850 he regards 

 it as an excretory pore, in 1858 as the anus. The change was 

 made in order to place the genus under the Bdellidea, where 

 Diesing was convinced it belonged if Mactra was its true host. 

 That the report of its occurrence in Ant Hope was an error 

 Diesing had discovered in the interval between 1855 and 1858, 

 and it was probably due to this discovery that the change in the 

 position of the genus was made (Diesing, 185S, p. 402). 



Diesing's disposition of Amphiptyches was apparently not 

 satisfactory to Wagener, for in his paper "Ueber Amphilina 

 foliacea, Gyrocotyle Diesing und Amphiptyches (Grube and 

 Wagener)" (1858), Wagener definitely withdraws Amphip- 

 tyches, recognizing his form to be a species of Diesing's older 

 genus. In Diesing's "Nachtrage und Verbesserungen zur Revision 

 der .Myzhelminthen" (1859), he agrees with Wagener in placing 

 the two species under one genus, which he refers to the "Bdel- 

 lidea monocotylea. " 



The two species are distinguished one from the other only 

 by the absence of spines and lateral frills and the smaller size 

 of the "tail rosette" in Gyrocotylt rugosa. 



Diesing (1859, p. 448) regards the genus as typically ecto- 

 parasitic on marine mollusks, assuming that the species of Grube 

 and Wagener has its normal habitat, not in Chimaera monstrosa, 

 but rather on some of those mollusks whose fragments occur in 

 the intestine of the fish. "Da Gyrocotylt rugosa aus einem 



