148 AMERICAN JOURNAL 



and Natural History. Repertory, London, 1865, and are well 

 illustrated by several excellent wood cuts of the more character- 

 istic forms. Mr. Tate entertains perfectly correct views of 

 the subject, so far as he goes ; but he is restricted by the limited 

 nature of the field to which he has confined himself. The ar- 

 rangement proposed by him is as follows : 



" Family Strombid^e, including the genera Strombus, Ptero- 

 cera, RosteUaria, Hippochrene, and the extinct genus Spinigera. 

 Family ApORRHAlDiE. — Genera: Aporrhais (=Chenopus), Stru- 

 thiolaria, etc., and the extinct genera Alaria, Diarthema and 

 Perissoptera.' ' 



In the first family he does not seem to be aware of the exist- 

 ence of several genera, or perhaps considers them subordinate 

 to RosteUaria etc. In the second, he takes Alaria in almost as 

 broad a sense as Morris and Lycett, including in it species both 

 with and without varices, and with the outer lip varying greatly 

 in style. Among other species included under this name is 

 RosteUaria carinata, almost a counterpart of Conrad's Anchura 

 abrupta in the peculiar form of the lip. He also describes a 

 subgenus of Aporrhais — Perissoptera — which he characterizes 

 as follows : " Spire elongated, anterior canal moderately short, 

 anterior sinus of varying distinctness, aperture dilated into a 

 nearly entire and broad wing, prolonged into a recurved point ; 

 wing applied against the last whorl but one, and not extending 

 on the lest of the spire; the columella lip very callous. The 

 wing is usually more or less entire, and broad, with a recurved 

 point; a few species have the wing narrow, rarely multidigitate. 

 Shell ornamented with transverse costse or tuberculose ribs." 



The essential points of the above description, when compared 

 with Anchura, are the length of the canal, and the character of 

 the outer lip. The first is of no value whatever. The canal 

 varies in length with every species. The other character is of 

 more weight, though not sufficient to warrant a separation ; An- 

 cJiura was based on a species with a f-sliaped lip, but every gra- 

 dation is found from that form to that of a sickle ; though I have 

 not seen a shell of this group that could be called bi- or multi- 

 digitate. The group which I have separated under the name of 

 Dicroloma, while closely allied to this, has an entirely distinct 

 style of outer lip, and the anterior canal is usually, if not always, 

 strongly curved. 



Unfortunately, I am not acquainted with the genus Diarthema, 

 given in the enumeration of the Aporrhaidos, having encountered 

 the name there for the first time. He furnishes no description, 

 or reference to type species, by which it can be identified. 



