360 NEW YORK STATE MUSEUM 



son. At an)' rate I have seen man) - specimens of the latter species which 

 correspond exactly to Emmons's figure. The number of thecae (24) 

 enforces this view. 



Like most of Emmons's species this is founded upon fragmentary, not 

 to say wretched material. The characters upon which he relied for specific 

 distinctions possess almost absolutely no value and in no other American 

 author's work are seen so many bad species based upon variable preservation 

 facies. 



d Diplograpsus ? sp. indet. 



Emmons, 1856. Am. Geol. pt 2, p. 236, pi. 1, fig. 3 



"It is thin olive-green and foliaceous, but its characters too obscure to 

 be determined with certainty." 



The only subsequent reference to this form appears to be that by Mr 

 Walcott, who regards this form as identical with his C 1 i m a c o g r a p t u s 

 emmonsi. But comparison of his [U. S. Geol. Sur. Bui. 30, 1886, p. 94] 

 description with Emmons's figure shows that this is impossible. For apart 

 from the great difference in the aspect of the two forms arising from a dif- 

 ference in the ratio of the squarish so called " denticles " to the interspaces 

 and also the trreat difference between the ratio of the leno;th of the " denti- 

 cles " to their breadth, the number of "denticles" (that is the number of 

 thecae) is entirely different. Mr Walcott's description of C. ? emmonsi 

 calls for 10 indentations in a distance of 1 1 mm, where the polypary is 4 mm 

 broad. Emmons's fragment is 4.5 mm broad, but it only has 5 or 6 thecae 

 to 1 1 mm, or taking the number in the usual comparison, we have for C . ? 

 e m m onsi about 23 to 25 mm ( 1 inch) as against 12 in the same space for 

 Emmons's form. Indeed the latter in a complete specimen would appear 

 not to have so many, as the last theca and its interspace indicates a number 

 of only 8 in the space of 25 mm ( 1 inch). 



Can we place Emmons's species ? Not very satisfactorily in the absence 

 of all data, especially locality and horizon. There is one American species 

 the general aspect of which it closely resembles, viz: C. p a r \ - u s Hall. 

 On the supposition that Emmons's figure is about three times natural size, 

 the form and dimensions of the polypary and the number of the thecae 

 and also (but perhaps to a slightly less extent) the proportions of the 

 length to the breadth of "denticles" and the ratio of the latter to the inter- 

 spaces, correspond fairly well with C. parvus. While all this is so and 

 while this is, as far as I can see, the only approximate reference of this frag- 

 ment, I can not feel any overweening confidence in the identity as it is hard 

 to see how Emmons could have found a fragment of C. parvus without 

 finding numerous perfect specimens associated with it. Still he apparently 

 was accustomed to rest satisfied with poor material, probably such as came 

 first to hand upon superficial search. 



