THE GASTROPODA 



'59 



pallium, which covers the whole 

 body and projects beyond in the 

 form of a siphon, and serves to 

 put the animal in communica- 

 tion with the external world 

 and for the passage of the ova 

 (Fig. 21) ; a foot is retained, and 

 also a nervous system and oto- 

 cysts ; neither eyes, branchia, 

 anus, nor rectum ; the stomach 

 is a sac with ramifying caeca ; 

 hermaphrodite ; parasitic in the 

 Holothurian Deima blalcei, in 

 the Indian Ocean. Entosiphon 

 forms the transition to the next 

 family. FAMILY 55. ENTO- 

 CONCHIDAE, Fischer ( = Cochlo- 

 syringia, Voigt). Neither shell 

 nor spirally coiled visceral mass ; 

 no sensory organs, nervous 

 system, branchia, or anus ; body 

 reduced to a more or less tubular 

 sac ; endoparasitic in Holo- 

 thurians ; probably all herma- 

 phrodite, with separate male 

 and female gonads ; incubatory 

 ( " viviparous " ) ; with conchi- 

 ferous and operculiferous veliger 

 larvae, without a retractor veli 

 muscle. Genera - Entocolax, 

 Voigt ; visceral mass essentially 

 genital and forming a swelling 

 surrounded by the pseudo- 

 pallium ; digestive orifice or 

 proboscis at the free extremity ; 

 orifice' of the pseudopallium at 

 the opposite extremity by which 

 the animal is fixed ; a second 

 accessory aperture of the pseudo- 

 pallium serves for the passage 

 of the genital products. Two 

 species parasitic in Holothurians 



.,,. .,... hntocolax ludungi, m situ, x 30. I, fixativn 



in the Tacmc : L. ludlVigi, in apparatus ; II, ovary ; III, uterus ; IV, buccal 

 Myriotrochus rinlcii from the oritice ; J .oviduct; vi, genital orifice; vn ova 



separated from the ovary, by dehiscence ; VIII, 

 Behring Sea (Fig. 138) ; and E. cavity around the ovary, formed by the pseudo- 



sclnemenzi in Chirodota pisanii 



from Chili. Entoconcha, J. Miiller 



(Fig. 139) ; body elongated and tubular ; the aperture of the digestive tract 



rudimentary and situated at the fixed extremity of the body ; protandric 



FIG. 138. 



