SOME NEW DEVON IC FOSSILS 273 



the young condition of S. crebristriata (a Schoharie grit 

 species in New York) represented by the original of plate it. 

 figure 13 [op. cit.] corresponds remarkably in size, contour and 

 surface with these. The shells in hand are quite regularly convex 

 having the greatest width along the hinge, a semielliptical marginal 

 outline and the surface bears 8 to 10 sharp angular but not ele- 

 vated plications, which increase in number by implantation so that 

 the margin bears at least four times as many plications as the 

 beak. In S. crebristriata, as referred to, there are about 

 the same number of plications though they are individually less 

 prominent and their duplication begins somewhat earlier. This 

 specimen shows a fine interlineation which we observe only at the 

 margin of the Gaspe shell. 



We construe this shell as a simple and early expression of 

 S. crebristriata, probably not attaining greater size or 

 more progressed development in surface feature than expressed in 

 our specimens. 



Dimensions. Length, 13 mm ; width on hinge, 16 mm. 



Lower Devonic. Grande Greve, P. Q. 



Stropheodonta parva Hall protype avita nov. 



See Hall. Palaeontology of New York. 1859. 4: 85, pi. n, fig. 5, n 



Several brachial valves show at first the median groove and four 

 to five simple strong ribs on each side, such as characterize 

 S. g a 1 e a t a Billings and change this expression by the simple 

 bifurcation of these ribs at about one half their length, and, close 

 upon the margin, by the subdivision of one or the other of these 

 branches. This is the character of S. parva Hall of the Scho- 

 harie grit of New York, a rare species, and comparison of the 

 Gaspe shell with the single exterior of the brachial valve figured 

 or known [op. cit. pi. 11, fig. 5] shows similarity of dimensions 

 to be accompanied with the like character of surface. In 

 S. parva the ribs are not so strong and bifurcation begins 

 sooner, that is, the period of simplicity continues longer in the 

 Gaspe shell and hence gives it more primitive expression, in accord- 

 ance with its antecedent date. 



Lower Devonic. Indian Cove, Gaspe, P. Q. 



Leptostrophia tardifi nov. 



Shell of uniformly medium size, averaging about that of 

 L. perplana (Conrad) ; flat or broadly convex in the umbonal 



