422 



MONOTOCARDIA — GYMNOGLOSSA — RACHIGLOSSA 



CHAP. 



Fig. 279. — Carinaria mediterra7iea Lam., 

 Naples: a, anus; br, branchiae; /, foot; i, 

 intestine; m, mouth; p, penis; s, sucker; 

 sh, shell ; t, tentacles, x |. 



a very small spiral shell. Carinaria (Fig. 279) has a rugose 

 translucent skin, visceral sac sub-median, apparently peduncu- 

 lated, covered by a capuliform shell. The larval shell, which 

 persists in the adult, is helicoid. 



Fam. 2. Atlaiitidae. — Shell spiral, operculate, covering the 



animal. Branchiae in a 

 ^ dorsal cavity of the man- 



tle ; foot trilobed, with a 

 small sucker on the meso- 

 podium. 



The shell of Atlanta 

 is discoidal and sharply 

 keeled, while that of Oxy- 

 gyrus is nautiloid, with the 

 spire concealed, no keel, 

 aperture dilated. 



((?) Gymnoglossa. — 

 Radula and jaws absent; 

 proboscis prominent, sexes probably separate, penis present. 

 The section is probably artificial and unnecessary, the families 

 composing it being, in all probabilit}', Taenioglossa which have 

 lost their radula in consequence of changed conditions of life 

 (pp. 79, 225). 



Fam. 1. Eulimidae. — Proboscis very long, retractile, mantle 

 forming a siphonal fold; shell small, long, subulate, polished; 

 suture shallow, aperture continuous, operculum present or absent. 

 Animal often parasitic, sucking the juices of its host by its long 



proboscis. Trias . Genera : Eulima (subg., Suhularia Ar- 



cuella^ Apicalia^ Mucronalia^ Stiliferi^ia, and others), Stilifer^ 

 Scalenostoma^ Niso^ and HoplojJteron. 



Fam. 2. Pyramidellidae. — Tentacles auriform, proboscis as in 

 Eulimidae, a prominent mentum or flap under the buccal orifice ; 

 shell usually small, conical ; suture shallow, apical whorls (the 

 embryonic shell) sinistral (p. 250), operculum corneous, pauci- 



spiral; nucleus excentrical. Trias . Genera: Pyirimidella 



(subg., Syrnola^ Otopleura^ Chrysallida^ Mumiola^^ Odostomia, 

 Eidimella^ Murchisoniella^ Turhonilla (subg., Dunkeria and 

 Cingulina. 



(d) Rachiglossa (p. 220). — Proboscis long, retractile; 

 siphon distinct, radula without uncini, sometimes without 

 laterals ; teeth strongly cusped ; shell generally wholly external. 



