TRENTON PERIOD. 6B 



height a slender outward-projecting spine. Tlie cells are of peculiar shape, 

 as shown in tlie enlarged figures on Plate IV, and their apertures appear to 

 have been lateral, but of this I am not entirely satisfied. If they are so, it 

 is rather remarkable that they are all upon one side, in view of the fact that 

 bilateral symmetry of the stipe is so prevalent tlu'oughout the family. 



This species has the general aspect of G. ramosus Hall from the dark 

 shales at Norman's Kill near Albany, New York, and before its microscopic 

 examination it was supposed to be identical with it. It is found, however, 

 to differ very materially in the form, of its cells and the character of the 

 stipe, as may be seen by comparing our figures with those of O. ramosus 

 on Plate A, Decade II, Greological Survey of Canada. 



Among these differences, there is one at least that seems to modify its 

 relation to the subgenus Climacograptus, and especially to that section of it 

 to which G. ramosus is assigned by Professor Hall. This is the presence of 

 inflated cells of iiTcgular form, projecting from the general surface of the 

 stipe, instead of having the cells short and square, and hollowed out of 

 the body of the stipe, — characters which are undei'stood to distinguish Cli- 

 macograptus. Among the specific differences between oiu* species and G. 

 ramosus are the different proportions and shape of the cells, the presence 

 of spines upon all of them in our species instead of upon a part only, and 

 the position of the spines about midway instead above the cell-aperture as 

 in that species. 



Position and locality. — Shales, probably of the age of the graptolitic 

 shales at Norman's Kill near Albany, New York; five miles north of Bel- 

 mont, Nevada, where it is associated with the three following-described 

 species. 



Subgenus DIPLOGEAPTUS M'Coy, 1850. 

 Graptolithus (Diplograptus) hypniformis White. 



Plate IV, fig. 4 a and h. 



Oraptolithus {Diplograptus) hypniformis White, 1874, Exp. & Surv. west 100th Merid., 

 Prelim. Rep. Invert. Foss., 12. 



Stipe simple, slender; sides flat; edges nearly straight and nearly 

 parallel; the increase in width from the proximal or basal end toward the 

 distal end being very slight, except near the base; serratm-es deep, narrow, 



