Ill MOLLUSCA PARASITIC ON ECHIXODERMS 77 



echinoids, where they probably subsist on the excreta, and are 

 sometimes found imbedded in the spines themselves. St. Turtojii 

 occurs on the British coasts on several species of Echinus^ and 

 Montacuta suhstriata frequents SpatangiiH purpureus and certain 

 species of EcJiinocarclmm^ Cidaris^ and Brissus. Lepton para- 

 siticum has been described from Kerguelen I. on a Hemiaster^ 

 and a new genus, Rohillardia^ has recently been established ^ for 

 a HijaUnia-'s\i^^ii(\ shell, parasitic on an Echinus from Mauritius. 

 (^e} Holothurioiilea. The ' sea-cucumbers ' afford lodgment to a 

 variety of curious forms, some of which have experienced such 

 modifications that their generic position is by no means estab- 

 lished. Entoconcha occurs fixed by its buccal end to the blood- 

 vessels of certain Synapta in the Mediterranean and the Philip- 

 pines. Entocolax has been dredged from 180 fath. in Behring's 

 Straits, attached by its head to certain anterior muscles of a 

 MyriotrocliusP' A curious case of parasitism is described by 

 Voeltzkow^ as occurring on a Synapta found between tide- 

 marks on the I. of Zanzibar. In the oesophagus of the Synapta 

 was found a small bivalve (^Entovalva)^ the animal of Avhich was 

 very large for its shell, and almost entirely enveloped the valves 

 by its mantle. As many as five specimens occurred on a single 

 Synafta. In the gut of the same Holothurian lived a small 

 univalve, not creeping freely, but fixed to a portion of the stom- 

 ach wall by a very long proboscis which pierced through it into 

 the body cavity. This proboscis was nearly three times as long 

 as the animal, and the forward portion of it was set with sharp 

 thorns, no doubt in order to enable it to retain its hold and 

 resist evacuation. Various species of Eidima have been noticed 

 in every part of the world, from Norway to the Philippines, both 

 inside and outside Holothurians.* Stdifer also occurs on this 

 section of Echinoderms.^ 



On Annelida. — Coehliolepas parasiticus has been noticed 

 under the scales of Acoetes lupina (a kind of ' sea-mouse ') in 

 Charleston Harbour.^ 



On Crustacea. — A mussel, f in. long, has been found ' living 



1 E. A. Smith, Ann. Mag. Xat. Hist. (6) iii. p. 270. 



2 Journ. de Conch. (3) xxix. p. 101. ^ Zool. Jahrb. Abth.f. Syst. v. p, 619. 

 4 See especially Semper, Animal Life, Ed. 1, p. 351. 



s Gould, 3foll. of U. S. eo'pl. exped. 1852, p. 207 {8t. acicula, from Fiji). 

 « Stimpson, Proc. Bost. 80c. N. H. vi. 1858. p. 308. 

 ■^ Pidgeon, Nature., xxxix. p. 127. 



