138 AMERICAN JOURNAL 



ively eliminated therefrom by others, and have served as con- 

 stituents of new genera, or been associated with previously es- 

 tablished ones. The propriety of the elimination of the forms 

 which have been referred to the genera Aporrhais and its dis- 

 memberments, Alaria, Biarthema^ Pterocerella, Dicroloma, and 

 TessaroJaz, may be at once admitted. With equal propriety has 

 Mr. Gabb eliminated P. speciosa, P. Dupiniana, and P. marginata, 

 all described by d'Orbigny, from the residuum, but the propriety 

 of combining those three together in one subgenus, to be con- 

 sidered as of Pterocera, is questionable, especially as the typical 

 species is not provided " with a straight or recurved canal ante- 

 riorly, and a canal ascending the spire posteriorly ;" or an 

 " outer lip digitate ;" its relations, indeed, appear to be rather 

 with the typical Strombidse. 



After all these eliminations, as Mr. Gabb has remarked, "in 

 the cretaceous and Jurassic formations are many shells with all 

 the characters called for in the commonly received definition of 

 Pterocera, but having a peculiar ' facies ' of their own," 

 yet from which, " except in general appearance [he] can find 

 no difference," and thus, by the latest reviser of the group, they 

 are left in Pterocera. This residuum, however, contains no spe- 

 cies to which the amended diagnoses of Pterocera and Harpago 

 are applicable, and it is by no means certain that any are at all 

 related to those genera. There are, however, two types which 

 have at least considerable superficial resemblance to them, and 

 which may possibly belong to the Strombidge, but such appears 

 to the writer improbable, and provisionally, at least, they may 

 be more advantageously retained among the Aporrhaidce. They 

 do not appear to have the sinus characteristic of the Strombidce ; 

 in one, indeed {Pt. 3foreausiana, d'Orb.), a sinus might be con- 

 sidered to exist, on faith of the illustration, but the appearance 

 is rather produced, there is reason -to believe, by the extension 

 of the anterior fascicle into an aborted lobe or digitation, and a 

 consequent emargination between it and the median digitation. 

 In order to secure for the forms in question due attention and 

 re-examination, it seems advisable to especially designate them, 

 but I have not had the opportunity of examining them, and de- 

 rive my information respecting them solely from d'Orbigny 's 

 " Pal^ontologie Francaise." 



HARPAGODES, Gill. 



Pterocera, sp. d'Orb., etc. 



Shell obconic or ovate-conoid, with the spire moderately ele- 

 vated, the canjil produced into a long digitation boldly recurved 

 towards the left, and the labrum m 



