STUDIES ON THE CILIATES FROM SEA URCHINS

¹ ZOÖLOGICAL LABORATORY, UNIVERSITY OF PENNSYLVANIA

1. Seven species of ciliates are described infesting Strotngylocentrotus dröbachiensis collected from the Bay of Fundy. This infestation is usually heavy and appears to be universal.

These ciliates are:

Entodiscus borealis (Hentschel)

Entodiscus indomitus Madsen

Cryptochilidium gracile n. sp.

Uronema sociale n. sp.

Plagiopyla minuta n. sp.

Euplotes sp. ?

Trichodina sp. ?

2. Four species of ciliates are described from the intestine of Toxopneustes variegatus, collected near Beaufort, N. C.

These ciliates are:

Cryptochilidium bermudense (Biggar)

Cryptochilidium echinometris (Biggar)

Anophrys vermiformis n. sp.

Colpoda fragilis n. sp.

3. Three species of ciliates are figured from the intestine of Strongylocentrotus lividus, taken from the Bay of Naples.

These ciliates are:

Cryptochilidium echini (Maupas)

Anophrys echini Di Mauro

Colpidium echini Russo

4. The relationship of these ciliates with their host is a rather loose one, for the ciliates in question are able to exist for some time in sea water and transmission seems to be orally. The youngest sea urchins examined were lightly infected. There is some evidence to point to a pathogenic rôle on the part of some of the members of the genera Cryptochilidium and Entodiscus.