OVILA. 255 



ities bluntly produced ; lip narrow margined ; posterior plica- 

 tion prominent. Length, 15-18 mill. 



North Carolina to West Indies, Brazil, 



Panama to California (Var.) 



In this species the color of its shell changes to correspond with 

 that of the gorgonia on which it feeds, either } r ellowish white or 

 purple. The synonymy includes 0. Antillarum, Reeve (tig. 41); 

 0. Canadiensis, Morch ; 0. Carolinensis, Morch ; 0. subrostrata, 

 Sowb. (fig. 42) ; 0. arcuata, Reeve (fig. 43). The following species 

 occurring on the West Coast of America are added, as I can find 

 no distinctive characters. It may be remarked, however, that so 

 far as I am able to judge from the figures and numerous speci- 

 mens, these West Coast representatives are always dark purple 

 with a lighter purple lip-margin coloring which somewhat rarely 

 obtains with the East Coast individuals ; on this account they may 

 be grouped under the best known, but not earliest name, as : 



Var. VARIABILIS, C. B. Adams (fig. 44). 



With this I include 0. Calif ornica, Reeve (fig. 45); 0. aequalis, 

 Sowb. (fig. 46), 0. livida, Reeve (fig. 47); 0. rufa, Sowb. (fig. 

 4^ ; 0. inflexa, Sowb. (fig. 49), and 0. Loebbeckeana, Weink. 

 (fig. 5d), which probably does not come from Vancouver's Island. 



0. AVENA, Sowb. PI. 5, figs. 51-55. 



Light purplish or rosy, wider than the preceding species, the 

 extremities shorter, often orange-tipped, lip-margin rosy-white. 

 Length, 12-20 mill. 



Panama to Monterey, Gal. 



The synonyms are 0. similis, Sowb. (figs. 52, 53), perhaps 0. 

 neglecta, C. B. Ad. (fig. 54), and 0. Vidleri, Sowb. (fig. 55). 



Subgenus CRITHE, Gould, 1860. 



0. ATOMARIA, Gould. 



Very minute, gloss}- white, somewhat acute at the extremities, 

 with a delicate groove at the summit ; aperture very narrow, and 

 uniformly so ; rostrum short, slightly recurved ; ventral laminae 

 directly transverse, about eight in number, as they pass into the 

 a pert urc, li'ivino- the appearance of course denticles on the pillar. 



