E. Billings — New Species of Stricklandinia, 61 



schock mountains, on the south side of the St. Lawrence, about 250 

 miles easterly from Quebec. I have never seen a specimen from 

 any other part of America. 



Stricklandinia Salterii, sp. n. — Plate IV. Figs. 2-2a. 



Spec. Char. — Shell transversely ovcal ; width greater than the length ; sides and 

 front usually rounded, but often with an obscure linguiform extension. Hinge-line 

 nearly as wide as the shell, straight and a little sloping on each side of the beaks. 

 Both valves are gently and uniformly convex. The ventral valve has often a barely 

 perceptible mesial sinus ; the umbo small ; the beak not incurved ; the area very 

 narrow, scarcely exceeding the thickness of the shell ; the foramen (as seen in 

 detached fragments) triangular and open to the beak ; the small chamber at the beak 

 almost exactly like that of S. loevis, and S. microcameriis, as figured by Sowerby, 

 M'Coy, and Davidson. The dorsal valve sometimes gives indications of an obscure 

 mesial fold ; but, in general, it is uniformly convex. I have not seen the area of 

 this valve, but it must be linear ; there is no umbo. Surface with several concentric 

 imbrications of growth, and with very narrow obscure ribs, three or four in twt) 

 lines, curving outwards to the sides, and some of them upwards to the hinge-line. 

 These are also crossed by fine concentric wrinkles. "When the specimens are 

 slightly exfoliated all the surface-characters disappear. 



Length of the largest specimen seen, twenty-five lines ; greatest width of the 

 same, at about the mid-length, thirty-three lines. Some of the specimens indicate a 

 greater proportional length. 



Ohs. — There is no other known species with which this need be 

 compared except S. Icevis, Sowerby, as described by M'Coy, under 

 the name of Pentamerus microcamerus (Brit. Pal. Foss., p. 210). 

 The width of that species, in proportion to the length, is stated to 

 be as fifty-five is to one hundred, whereas in this it is, on an average, 

 about eighty to one hundred. This great difi'erence in proportions 

 rarely occurs in the same species. Messrs. Davidson and Salter are 

 of opinion that McCoy's P. microcamerus is identical with S. lens. 

 Be that as it may, the figure of S. Icevis, given by Sowerby in 

 *' Sil. Syst.," pi. xxi. fig. 21, seems to be distinct from ^S. lens, and 

 also from S. Salterii. He says {Op cit., p. 638), "Semicircular, 

 compressed, smooth ; a slight elevation along the middle ; beaks 

 rather prominent, the area between them narrow, with parallel 

 edges. Length, eight lines ; width, twice as much." The words 

 " elevation along the middle " could only apply to the dorsal valves 

 of S. lens and S. Imvis, in neither of which can the dorsal foramen 

 be seen, when viewed in the position in which Sowerby's specimen 

 is drawn, as it is in the figure cited. This figure, however, always 

 appears to me to exhibit a sinus rather than a fold, in which case it 

 would be a ventral valve. Judging from Mr. Davidson's figures, I 

 should say that the upper part of the ventral valve of S. lens must 

 be of a very different form from that of the specimen represented 

 by Sowerby. 



Position and locality. — Stricklandinia Salterii occurs at Heath 

 Point and Cormorant Point, Anticosti, in the Anticosti group, 

 division 3 = to the Upper Llandovery rocks. 



Besides these two species there is a form with the ribs straio-ht, 

 which may possibly be a variety of S. Davidsonii. It occurs at 

 Anticosti in the same beds with the others. 



In describing Stricklandinia 1 unfortunately stated that '' This 

 genus includes three English species, which have been long known 



