THE NAUTILUS. 35 



basal one not being described as bifid, and being about equal to the 

 next tooth in size, and no axial tootb is developed. 



P. Clappi is a very interesting addition to the sub-genus Labyrin- 

 thus. It will be interesting to know what snail-eating mollusk or 

 arthropod inhabits the northern part of South America, where this 

 type of shell is developed, that is absent in southern Colombia and 

 Ecuador, where the almost toothless group Isomeria occurs. 



This species is one of the most interesting of Mr. Herbert H. 

 Smith's finds in the Sierra de Santa Marta. It is named in honor 

 of my friend Geo. H. Clapp. 



GENERAL NOTES. 



Truncatella truncatula (Drap.) in the United States — 

 In preparing the Catalogue of North American Land Shells, this 

 species was inadvertently overlooked. It has been recorded by 

 Prof. Verrill, in the Proc. U. S. Nat. Mus., Ill, 376, and Trans. 

 Conn. Acad. Arts & Sci., V, 525, fig. 8, as follows : " Living in 

 considerable numbers, and of all ages, among the docks at Newport, 

 E. L, July, 1880. It occurred among decaying sea-weed thrown up 

 at high-water mark, both among the vegetable matter and on the 

 under side of stones." " Common en the coast of Europe, and in 

 similar localities. Perhaps introduced on this coast by shipping, 

 but it may have been hitherto overlooked. It was associated with 

 Assiminea grayana and Alexia myosotis.'' — C. W. J. 



An Evolving Ashmunella Ashmunella thomsoniana cooperce, 



n. var Shell with max. diam. from 13 to 15 millim., but usually 



of the smaller size ; basal tooth single, occasionally slightly double ; 

 umbilicus narrower than in type or var. porterce, exposing less of the 

 penultimate whorl; genitalia as in porterce, with the same long (22 

 mm.) spermatheca, and double insertion of the penis retractor. 

 Hab — Las Vegas Hot Springs, 1900, 1901. Discovered by Miss 

 Mary Cooper; later taken in quantity by Miss Cooper and Miss 

 Maud Ellis. The locality is in the Transition Zone, at about 7,000 

 ft. altitude ; porterce belongs to the Canadian Zone, about 1,000 ft. 

 higher. This is not a very distinct form, conchologirally ; but is 

 worth calling attention to as a species of Ashmunella in the making, 

 probably derived from the porterce form rather than from the true 

 thomsoniana T. D. A. Cockerell. 



