PROTOZOA AND OTHER ANIMALS 921 



of Anophrys, A. sarcophaga Cohn, which has been discussed above as a 

 facultative parasite of crabs. Kahl (1934) suggested a relationship of 

 certain of these ciliates to Philaster digitijonnis, which occurs, as men- 

 tioned above, on the body of starfish. He was doubtful about the cor- 

 rectness of their position in the genus Anophyrs. There is confusion 

 about the taxonomy of many sea-urchin ciliates. 



Genera that are restricted to sea urchins, and may be supposed to have 

 evolved in the shelter of these hosts, are Lechriopyla Lynch, Entorhipi- 

 dium Lynch, Entodiscus Madsen, Bigggaria Kahl, Madsenia Kahl. Cryp- 

 tochiltdium Schouteden, in part included in Biggaria, has a species in 

 the annelid Phascolosoma vulgaris. 



Lechriopyla mystax Lynch, commensal in the Pacific Coast sea urchins 

 Strongylocentrotus jranciscanus and S. purpuratus, is closely related to 

 Plagiopyla. It is markedly thigmotactic: "Although almost continuously 

 in movement [it] adheres almost constantly to surfaces. The large 

 peristomal groove seems to act as a sucker" (Lynch, 1930). Lechriopyla 

 apparently has diverged from Plagiopyla in relation to its obligatory 

 endocommensalism, but there are no profound alterations. 



Four species of Entorhipidimn were distinguished by Lynch (1929) 

 in Strongylocentrotus purpuratus in California. None of these flattened, 

 fan-shaped trichostomes was present in 5. jranciscanus from the same 

 localities, so there seemed to be marked host-specificity. Uyemura 

 (1934), however, found one of the same species in another sea urchin 

 of Japan, and described a new species, E. fukuii, which occurs in five 

 hosts of four genera. 



Related to Entorhipidimn is Entodiscus, represented by E. horealis 

 (Hentschel) from several different hosts of the North Atlantic and 

 Japan; and E. sabulonis Powers found in all individuals examined of 

 two species of Clypeaster at Tortugas. E. horealis is present in great 

 abundance and, with its greatly flattened form, probably in appearance 

 and occurrence suggests Opalina in Amphibia. According to Powers 

 (1933b), besides swimming about in the lumen of the intestine, it ad- 

 heres by the ventral side to the intestinal mucosa. The food vacuoles, he 

 stated, contain rods, probably bacteria, and objects resembling nuclei of 

 epithelial cells. At that time Powers thought that the ciliate might attack 

 the intestinal mucosa, secreting cytolytic enzymes, thus being definitely 

 parasitic; but later (1935) he did not stress this ill-founded conclusion. 



