OBISKANy FAUNA OF BECRAFT MOUNTAIN 43 



There is, farther, a notable breadth to many of the specimens, which 

 is not so marked in normal individuals. Many of the examples empha- 

 size the close approximation of this species to the Lept. acutipli- 

 cata Conrad, of the Onondaga limestone. This resemblance is particu- 

 larly noticeable in the pedicle-valves, but the broader and more sharply 

 angular plications of the latter species and the more depressed brachial 

 valve constitute reliable differences. Prof. Hall, in 1867, pointed out 

 the similarity of Lept. flabellites and L. acutiplicata, sug- 

 gesting that the two might prove to be identical. 



Trematospira multistriata Hall 



Plate 6, flg. 1-4 



1859. Trematospira multistriata Hall. Paleontology of New York. 3 : 209, pi. 24, 

 fig. 3a-t ; 28, fig. 5a-f 



1892. Trematospira multistriata Clarke, op. cit. p. 414 



(?) 1857. Spirifer perforatus Hall, Descriptions of new species of fossils, p. 60 



1859. Trematospira perforata Hall, Paleontology of New York. 3 : 208, pi. 28, 

 fig. 3 a-i; 8, pt 2, pi. 49, fig. 5, 6 



According to the original descriptions, the distinguishing feature in 

 the species above cited is the stronger fasciculation of the plications in 

 T. perforata. It is noted also that in T. multistriata re- 

 peated duplication of the plications may occur. The specimens of 

 Trematospira from the Oriskany agree in general features with 

 the above species, though none have been seen which attain the size 

 often reached by T. multistriata. The plications are sharply 

 angular, with a broader, outer slope, specially near the median fold and 

 sinus. These are sometimes simple throughout their course, but gener- 

 ally are duplicated at irregular intervals, the result of which is a strong 

 fasciculation of the surface, the few early ribs which start at the um- 

 bones maintaining their prominence over the shell. This fasciculate 

 effect is probably more pronounced in the majority of cases than is 

 usual in normal specimens of Tremat. multistriata, but it would 

 be impracticable to divide the Oriskany specimens on the basis of this 

 character. On the other hand, their variation in surface characters 

 serves to indicate the probable unity of those two Helderbergian species. 



The surface is finely granulose and punctate. 



