OF CONCHOLOGY. Ill 



and peculiar in young shells, which usually have only one spiral 

 ridge on the columella, while the adult form has two. These 

 are not mere nodules, as might appear on a cursory examination, 

 but regular spiral ridges, extending through nearly all the 

 whorls. 



This is very readily shown by a section, exposing the colu- 

 mella. 



Family COLUMBELLID^E, Moerch. 



Genus AMPHISSA, H. and A. Adams. 



Amphissa, H. and A. Ad., Gen. Rec. Moll, i, p. 111. 

 Trunearia, Cpr., not Ad. and Rve. 

 Amycla, Cpr., not H. and A. Adams. 

 Buecinum, sp., Rve. 



This genus was considered by the Messrs. Adams as a subgenus 

 of Oominella, with which it has very little affinity. The animal 

 of the typical species resembles in general appearance that of 

 Oominella, as figured by the brothers Adams. The teeth are of 

 the Columbelloid type, and indicate its family position. The 

 operculum, whatever may be its value in other groups, is of little 

 value anions the Columbellidce for determining affinities. This 

 has been clearly shown by Moerch, and it is to be regretted that 

 Dr. Carpenter, in his works on the shells of the West Coast, has 

 ignored this fact. 



Type Amphissa corrugata, H. and A. Adams, 1. c. 



Buecinum corrugatum, Rve. 

 Trunearia corrugata, Cpr., part. 

 Amycla corrugata, Cpr., part. 



This species has been confounded with the following one by 

 Dr. Carpenter, under the above names, under which it has been 

 extensively distributed. 



Amphissa versicolor, Dall. 



Amphissa versicolor, Dall, MSS. 1866. 



Trunearia corrugata, Cpr., part. Suppl. Rep. p. 662, 1863. 

 Amycla corrugata, Cpr., part. MSS., labels, &c. 

 Amycla undata, Cpr., MSS., labels, not Cpr., Suppl. Rep. p. 

 662, 1863, per types. 



This species was first distinguished by me in the MSS. already 

 alluded to, in 1866. It had previously been confounded with 

 the corrugata, and has since been confused (in MSS. labels at 

 least) by Dr. Carpenter, with his "Amycla" undata, which, 



