206 CORALLIOPHILA. 



would prevent escape, can scarcely be sustained. We do not 

 know how many of the species allied to the type of the genus 

 ma}^ partake of this singular mode of growth ; it has only been 

 observed in R. antipathic us. A large number of species have 

 been grouped by Messrs. H. and A. Adams in a subgenus Coral- 

 liophila, the character of which is, that they do not (are not 

 known to) form this shelly enclosure. If this supposed differ- 

 ence of habit should be proved by observation, there can be no 

 doubt that the two names should be generically separated. It 

 may be remarked that no lingual denticles have been found in 

 the animals of Coralliophila, Leptoconchus or Magilus examined 

 by Troschel. Coralliophila possesses an operculum ; I do not 

 know whether the younger stage of Rhizochilus has one or not, 

 but the presumption is that it has not. 



Several species have been described, besides the type ; but as 

 the latter only has been observed with the closed aperture, I 

 think it better to refer the others to Coralliophila. 



R. ANTIPATHICUS, Steenstrup. PI. 65, figs. 348-350. 

 Shell thin, whitish. Length, 1 inch. 

 When adult, grasping the axis of Antipathy* ericoides. 



Coralliophila, H. and A. A<i. 



A large number of specific forms have been described, many 

 of which have not been figured. Judging from the extreme 

 variabilit3 r of the well-known species both in form and sculpture, 

 it may be anticipated that most of the more recently characterized 

 species will prove to be synonyms, and as the diagnoses alone 

 are insufficient for their determination, I have placed the names 

 of these species at the end of the genus, as doubtful. 



C. NERTTOIDEA, Lam. PI. 65, figs. 353, 355, 356 ; PI. 66, fig. 375. 



White ; light purple within the aperture. 



Length, 1-1 '5 inches. 



Central Pacific. 



Purpura violacea, Kiener (figs. 353, 375), is undoubtedly the 

 same species and P. gibbosa (fig. 356) is a form with the scabrous 

 revolving stride well developed. TricJiotropis Orbignyana, Petit 

 (= Purp. Trichotropoides, Montr, (fig. 355), from New Caledonia 

 is the latter form not yet adult. 



