310 Review of the New York Geological Reports. 



Fig. 1 is the most abundant trilobite at Lockport ; it is closely 

 allied to the A. longicaudatus of the Wenlock shale of England, 

 differing from it only in having the tail less attenuated and hav- 

 ing fewer ribs in the post abdomen. We are not aware that this 

 species has yet been found in the West. 



The Calymene, fig. 3, has until lately been referred to the 

 C. Bliunenhachii. and so also has a Trenton species, [C. senaria,) 

 but these are probably so many distinct species. The Niagara 

 Calymene is more obtuse, according to Hall, in the posterior an- 

 gles of the buckler than the Blumenbachii, and has fewer artic- 

 ulations (13) in the back ; the protuberances of the middle lobe 

 are less prominent in the Niagara species than in the Blumen- 

 bachii. Casts of a Calymene have been found in the " cliff for- 

 mation" of the West, bearing a strong analogy with the Niagara 

 species. These casts do not however, exhibit any terminal mar- 

 gin-band in front of the buckler, and the surface of the buckler 

 appears quite smooth and not covered with pustules, as is the 

 case with the C Blum,e7ibachii, and appears also to exist on the 

 Niagara species, so far as can be judged from the figure given in 

 the New York Reports. 



Figure 4, is supposed to be identical with the Bximasiis Bar- 

 riensis of the Wenlock limestone. It is known at Lockport, 

 where it is found in the shale, as the "double-headed trilobite." 



The magnificent species, Uomalonotus delphinocephalus, is 

 also a common trilobite at Lockport. 



It is regarded as the same species figured in Murchison's Silu- 

 rian Researches under this name, and found in the upper beds 

 of the Wenlock limestone. That author has the following re- 

 marks regarding the identity of the English and American spe- 

 cies. " As I can discover no difference between our Homalo- 

 notiis and the American Trimerus delphinocephalus, (Green.) 

 except in size, (the latter being very diminutive.) I have retained 

 the specific name of the American author, while I adhere to the 

 generic name of Konig, which was applied to bodies of this 

 form before the publication of Dr. Green." The specimens of 

 this species found at Lockport are from eight to twelve inches 

 in length ; they cannot, therefore, be much smaller than those 

 found near Dudley Castle in England. 



Hall says this trilobite has been confounded with the Dipleura 

 Dekayi of the Hamilton group. He asserts that the nature of 



