ILDICA. 173 



Hancock," CHENU, Manuel de Conch., p. 416, f. 3087. Runcina 

 viridis F. & H., Hist. Brit. Moll., iii, p. x of index (error). 



The species varies considerable in intensity of color, and some- 

 times lacks light rings around the eyes. They are extensile and 

 very active. 



Vayssiere found a very minute, delicate, non- calcareous disk be- 

 neath the hinder part of the mantle, which may be the vestige of a 

 shell. 



R. PRASINA Morch. PI. 68, figs. 42, 43. 



Body linear, elongated with subparallel sides, the anterior margin 

 lightly curved inward ; mantle green, with regularly spaced, close, 

 minute warts, the posterior margin three-lobed, the median lobe 

 smallest ; dorsal part of mantle elevated, convex, of a deeper color ; 

 eyes black, very far apart toward the front. Foot slightly wider 

 than mantle, somewhat projecting and broadly rounded behind ; 

 yellowish-green. Stomach-plates (fig. 43) nearly semi-circular, with 

 rather remote, obtuse, strong and arcuate teeth. 



Length about 4 mill. (Morch}. 



St. Croix, West Indies, near Christianstad (CErsted). 



Pelta pmsina MORCH, Journ. de Conchyl., 1863, p. 42. BERGH, 

 Malacol. Unters., iv, 1872, pi. 24, f. 27-29. 



It is narrower than R. coronata, with the mantle trilobate behind 

 and the eyes more anterior. Morch 's description and Bergh's fig. 

 ures were from drawings by (Ersted. 



Genus ILDICA Bergh, 1889. 

 Ildica BGH., Malac. Untersuchungen, iii, Anhang, p. 869. 



Noteeum continuous, the mantle-edge projecting somewhat over 

 the sides of the body all around. Shell small, posterior, uncovered. 

 Branchial plume simple, posterior on the right side of body, pro- 

 jecting. Head small, with a small tentacle on each side of the 

 mouth. Foot rather broad, tail short. 



Labial armature composed of minute rods. Radula with median 

 teeth and hamate laterals. Stomach armed with 4 strong dentic- 

 ulate triturating plates. 



Ildica has an external resemblance to Pleurobranchus, on account 

 of its extended notreum. 



