W. B. DWIGHT. 151 



long a full discussion of this very difficult and inter- 

 esting subject. Microscopic sections have revealed 

 other unsuspected minute corals of various genera, not 

 yet sufficiently examined for description. 



In the calciferous group, in addition to the gastero- 

 pods, Holopea of unknown species, Ophileta covipacta, 

 complanata, and sordida, formerly reported, there are 

 several species of Raphistoma, one new species of Bu- 

 cania, probably several new species .of Ophileta, and a 

 large species of what is perhaps Ilelicotoma. Of brachi- 

 opods, there are one or more species of Orthis and Lep- 

 toma ; also, Triplesia (Carrier ella) calcifera, a fossil of 

 the Canadian calciferous, in large numbers. Of trilo- 

 bites, by blasting at Rochdale, I have found a sufficient 

 number to describe two new species provisionally under 

 the genus Bathyurus, to which they do not thoroughly 

 conform. One of these species has a smooth and exceed- 

 ingly convex glabella ; the other has a glabella covered 

 with pustules and of very low convexity. 



Of the orthoceratites I can only say that after over 

 three years labor on them, I have at last worked them 

 up sufficiently to begin to publish descriptions of some of 

 them. In the April number of the American Journal 

 of Science, I have described and illustrated by a plate, 

 six new species of orthoceratites and the two species 

 of trilobites above mentioned, from this limestone. A 

 large and fine cyrtoceras, with an elliptical marginal 

 siphon, which is one of the most abundant, I have named 

 Cyrtoceras vassarina. The five other orthoceratites de- 

 scribed are named as follows : Orthoceras spissiseptum. 

 and henrietta, Cyrtoceras dactyloides, and viicroscopi- 

 cum and Oncoceras oasiforme. Of the trilobites, the 

 smooth one is named Bathyurus taurifrons, and the 

 pustulated one, B. crotalifrons. I hope to follow up 

 these descriptions very soon by others. It is as yet im- 

 possible to give a very near estimate as to the number of 



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