GENERAL FEATURES, METHODS, ETC. 25 



carinnla and Slulonwnid sdlirilori. crawl alioul freely over the sea Ixittoin, tliiiui:;li 

 it is possible also that tliev haxc been loosened IVoni some host. 



The relation of mollusc and coelenterate has not Ix'cn thorouji;hl_v worked 

 out, but there are many indications and some definite proof that it is a genuine 

 case of parasitism ami not an accidental association or a case of commensalism. 

 In Dn-panomenid nnnpjii-illd from Ihe Hawaiian Islands the jjroboscis of one 

 indi\idual was inserted into the body wall of some s])ecies of E])izoantIius, many 

 of whose reproductive and other cells had been withdrawn so that htn-e therc> is 

 no doulit that this Solengastre is a i)arasite. The ])resence of nematocysts in 

 the alimentary canal of se\'ei'al other species, includinij; most of the sjiecies of 

 Strophomenia, indicates that they likewise are in the same category. Iliibrecht 

 ('80) states that a bit of alcyonarian coi-al was found in the mouth (if /'. sluiliri, 

 but he calls attention also to th(> fact that diatoms and entomostracans occurred 

 in the faeces in the cloacal cavity, and Heusclier ('1)2) recoids the presence of 

 Entomostraca in the gut itself. It thus develops that the diet of sucli species 

 is varied, and it is possible that such forms as P. r<((/(ms and P. ckfiidcrutu which 

 were found crawling about on plants belong to this same class. 



yo far as known the food of the C'haetodermatidae consists of mic-roscupic 

 organisms and organic I'emains which they scoo]) up while bui-row ing through 

 the ooze. Wireii ('92) believes that the buccal plate (Mundschild) acts as a 

 digging organ, and this may intleed be the case but the exceedingly small amounts 

 of inoi'ganic matei'iaJ, which make their wa\' into the digest i\'e tract, indicate 

 that in addition to functioning in a jiurely mechanical fashion it manifests a 

 decided selectix'c action. \Mien selected the food is cari'ied backwju'd by the 

 great conical tooth in the genus Chaetodei'ma, atui in the foi'm of a more or less 

 spherical bolus, mixed with the secretion of the salivary glands, is carried into 

 the mid gut. In Prochaetodernia and especially Limifossor the I'adula and its 

 supports are of large size and indicate active, predatoiy habits, l>ut the contents 

 of the gut are essentially the same as in Chaetodernui. 



Color, Size. — In a ])reserved state the skin of the Solenogast res is usually 

 unpigmented, the light yellow or yellowish brow n tint of [Iw animal being due to 

 the cuticle investing the body. In many species, especially of thcChaetoder- 

 matidae, this may be obscured to a greatei' or less degree by the nuiltitudes of 

 refringent sincules imbedded in it or by some of the internal organs. The liver 

 for example is often dark brown, and shining through the translucent body wall 

 and the overlying cuticle and spicules, giv(>s a decided frosted gray tint to several 

 species. The red color of the Ijlood plasma may imj)art a pinkish tinge espe- 



