128 K. J. Bush — Jlarine Gastropods referred to 



They are about half the size of a full-grown trilix and differ from 

 specimens of that species of the same size, in lacking the distinct 

 tricarination of the whorls, in having the whorls more convex and 

 more regularly coiled, so that the body-whorl is not so abruptly 

 enlarged, in having the spire relatively larger, and in the striation of 

 the umbilicus. Both specimens of supranitidus have three conspic- 

 uous revolving threads separated by deep grooves in the umbilicus; 

 one has a very prominent basal carina, the other has it but partially 

 developed; in this specimen the whorls are perfectly smooth, while 

 in the former the two faint upper carinse commence just back of the 

 aperture; neither show any trace of the microscopic striations found 

 in trilix. In the many specimens of the latter which I have, there 

 seems to be no vai'iation in the size of the small nucleus, the rela- 

 tively much smaller spire and abrujjtly enlarged body-whorl (a pecu- 

 liarity which becomes more marked as the shell increases) and in 

 the strong tricarination of the whorls, even in very small specimens. 

 They differ only in the number and prominence of the threads in 

 the umbilical region, and in the distinctness of the microscopic stria- 

 tions on the upper part of the whorls. The constancy of these char- 

 acters ought to prove that the two species are quite distinct. 



The four species, besides siihcarinatus (Montagu), included in 

 Adeorhis by Wood present two quite distinct forms ; pulchralis, 

 which bears a strong resemblance to a Margarita, and supranitidus, 

 tricarinatus and striatus, which are quite different. Of these, supra- 

 nitidus has caused the most confusion in synonymy, as no two 

 writers seem to agree as to what it really is. As mentioned above, 

 Mr. Jeffreys identified it as a fossil variety of Trochus Duminyi 

 Requien, but in vol. v, B. C, 1869, he mentioned that that species 

 should fall into the synonymy of Solarium Philippii Cantraine. 



In 1878, Prof. G. O. Sars described and figured, as supranitidus 

 Wood, a very minute Norwegian shell,' referring it to the genus 

 Omalaxis. He stated that the spire is plane, not elevated; suture 

 profoundly impressed, etc, etc. At the same time he defined the 

 genus Adeorhis Wood, and described and figured a species very 

 different in form from subcarinatus (Montagu), but closely resem- 

 bling /)MfcAra?«s Wood, with which Mr. Jeffreys compares it (Proc. 

 Zool. Soc, London, p. 41, Jan., 1885). Prof. Sars places both genera 

 in the family Solariidae at the end of the Gymnoglossa. 



' For this very distinct species, which does not seem to be ver_y closely related 

 generically to Circuhis, T propose the name Sarsi, but very much doubt its near rela- 

 tion even to Omalaxis. 



