284 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1855. 



Habitat. — \Ycsteru shores of British Islands from Slietlaud to Sarlv, 

 aud southward to Madeira, the Mediterraneau and iVdriatic Seas. In- 

 troduced on the coast of Xew Eughiud, iSTorth America. 



This species differs from Mdampus only in the form of the shell, which 

 is more elongate, aud in the absence of lirai ou the outer lip. The poste- 

 rior ijartof the foot shows a slight tendency to indentation, but not less 

 than some Si)ecies of Alchnnpua, as it appears this character is somewhat 

 variable. . The shell, except in its smoother epidermis and obsolete 

 posterior parietal denticle, is almost exactly like the lighter colored 

 forms of Alexia myosotis, a fact which has led to much confusion. 

 There is gften a single projecting point ou the thickened outer lip, more 

 i'requently in American than in European specimens. The posterior 

 denticle, too, is more frequently developed in American examples. Mr. 

 Binuey, while recognizing that the description of the animal by Dr. 

 Gould did not agree with that of the genus Alexia, nevertheless referred 

 the species to Alexia myosotis. 



I have very little doubt that Kuster's description was intended for 

 this shell ; his figure does not agree with his text, but, nevertheless^ 

 might have been badly drawu Irom a short stout specimen of this 

 species. 



It is probable that the true Alexia myosotin is found ou the coast of 

 New England with this shell and that they have been confounded with 

 each other. This can only be determined by an examination of the 

 living animal, but some specimens of the shells I have seen exactly 

 agree with the Alexia. Both of them have probably been introduced 

 on ballast or otherwise from Europe. It is very probable from Dra- 

 l^arnaud's text that he may have confounded the shells of the two forms, 

 but he carefully describes the animal of his Auricula myosotis, and this de- 

 scription says nothing of the division of the foot, which he certainly 

 would have noticed had he examined living specimens of Leuconia. 

 The dentate form (var. ringens Turton and Jeffreys) was not known to 

 him aud was described by Michaud, in his supplement to Draparnaud's 

 work, issued in 1839, as CarycMuni personatum. 



The name to be adopted for the group we have termed Leuconia is 

 still somewhat doubtful. I have been unable to examine Bivona's 

 pamphlet in which the genus OvaMla is described. The only references 

 to it which convey much information are those of Philippi and Gray. In 

 Turton's IManual Dr. Gray refers to Ovatella as the equivalent of Alexia 

 as late as 1857, perhaps following Moquiu Tandou, but ten years before 

 he had referred to " Ovatilla Bivon " as in part equivalent to Leuconia, 

 and to Alexia as equal to " Ovatella Gray, 184<», not Bivon" (P. Z. S., 

 1847, p. 170). Philippi quotes Bivona for Ovatella bidentata Bivona non 

 Montague (= 0. Bivoruc Phil.), which is Bivona's third species, his first 

 being 0. polita {= Auricula {Melampus) conoidea Fer. fide Philippi), his 

 second being O. punctata Bivona { = Atiricula Firminii Payr. tide Phil- 

 ippi, — Monica H. & A. Adams), while another of Bivona's species is 



