NO. 1395. CAMBRIAN BRACniOPODA—WALCOTT. 305 



IPHIDELLA NISUS, new species. 



Ventral valve rather low, with the apex overhanging' the posterior 

 margin. Surface marked by very fine lines of growth with still liner 

 bands of stria^ between them. About 10 very tine, radiating i4dges 

 extend from near the apex to the front and lateral margins. 



This little shell is represented by a single specimen of the ventral 

 valve from the conglomerate limestones near Bic. The associated fauna 

 included fragments of Olenellus. 



I was at first inclined to refer this shell to /. sculpt'dh or I. jjeall; but 

 the overhanging apex and strongly marked surface, and the fact that 

 there is an interval of :?,000 miles between the species, led me to sepa- 

 rate them. Stratigraphically the two latter species occur in the Middle 

 Cambrian and nhm in the Lower Cambrian. I think the two forms 

 forms should not be included in one species. 



Forriiation and locality. — Lower Cambrian. In a bowlder of the 

 limestone, 2 miles w^est of Bic Station, Province of Quebec, Canada. 



IPHIDELLA, species undetermined. ^ , ,< -^ ', 3^^ 



Iphidea, sp. undet. Walcott, Mong. U. S. Geol. 8ur., XXXII, 1899, p. 449, pi. 



LX, fig. 6. 



Dorsal valve, semicircular, slightly convex. Hinge line somewhat 

 shorter than the wndth of the shell below; nearly straight, the rostral 

 angle about 180°. Beak small, not elevated. Surface ornamentation 

 consists of extremely tine radiating and undulating concentric stria? 

 that can be seen in detail only with a strong magnifying glass. Shell 

 substance horny. 



This form is associated with /. sculj^>t!lls and, judging from external 

 characters, is closely related to it. The surface ornamention is of the 

 same character, and in the absence of the ventral valve it is difficult to 

 distingiash an}- specitic characters on which to base a new species, 

 although the shell is much larger than that of typical I. sculptilis. 



Forination and locality. — Middle Cambrian. Flathead terrane (low- 

 est fossiliferous bed); Crowfoot section, (xallatin range, Yellowstone 

 National Park, Wyoming. 



IPHIDELLA LABRADORICA ORIENTALIS, new variety. 



Only one dorsal valve of this shell occurs in the collection. Its gen- 

 eral form and surface characters are very much like those of I_phideHa 

 lahradorica swantonensis. The varietal name is given more on account 

 of the fact that this shell occurs in China and the variety mcantonensis 

 on the eastern side of the North American continent than from any 

 marked differences between the shells from the two localities. It may 

 be that with a good series of shells from China differences would be 

 found that are not to be determined with only the single shell for 

 comparison. 



