92 POSSIL ESTHERI.E. 



the same occur sufficiently distorted, or otherwise modified, to be sketched hke the rough 

 figures, above alluded to, which are copied at pages 86 and 87. 



Further, Mr. Conrad appears to have identified P. muUicostata with P. ovata (Lea), 

 and P. triangularis with P. parva (Lea) ; and of Lea's species we can judge by our own 

 Pennsylvanian specimens, which agree with those from Richmond and Dan River, there 

 being evidence of one species only. 



Of P. ovalis, Emmons, we learn, that it is " common in the shales of the Richmond 

 basin," as well as in the Lower (Chatham) shales of the Deep River series ; and, indeed, 

 the Dan River series is mentioned in connection with its occurrence. At all events, it 

 appears that we may expect to find it among our Richmond specimens ; and hence I 

 believe that it merges, with the rest, into the one species which appears to have an 

 enormous range, horizontally and vertically, in this great series of Lower Mesozoic 

 deposits in North America. 



Li 1857 a few specimens of fossil EsthericB from the black shales of Pennsylvania, 

 Virginia, and North Carolina, were confided to me by the Professors W. B. and H. D. 

 Rogers. Though some of these seemed at first sight to be tolerably well preserved, and 

 to belong to two or even three distinct forms, yet, on examination, the difficulty of discri- 

 minating any real differences of feature and structure has been found to be very great, if 

 not impossible. The results, however, arrived at as to the determination of species is 

 given above. 



I cannot make as full and exact a comparison of the North American fossil Estheria 

 with those of Mangali and of other places as I should have wished ; but we can learn 

 much respecting the paleeontological associates of the Estheria, and of the probable mode 

 of the deposition of the strata in which they are found, from the accounts given of the 

 Estherian shales of Pennsylvania by the geologists of the United States. 



The Estheria, accompanied by Cyprida, occur in the " Main Red Sandstone belt in 

 Pennsylvania, Virginia, and North Carolina," in the short intermediate tract of Red Sand- 

 stone in Virginia, and in the more eastern tract in Virginia and North Carolina. Without, 

 however, availing ourselves of the full descriptions of these strata given by Rogers,^ 

 Emmons,* and others, it will be sufficient to take the section exhibited by the cutting of 

 a tunnel on the Reading railway at Phcenixville, Chester County, Pennsylvania, described 

 lately by Mr. Wheatley ; and this is the more interesting as the author gives a critical 

 resume of the reptihan and other remains found in the same group of strata, and offers 

 some remarks on the apparent similarity of these with the Nagpur and Mangali beds. I 

 therefore avail myself of the following communication made to the ' American Journal of 

 Science and Arts,' 2nd ser., vol. xxxii (No. 94, July, 1861), p. 41, &c., mentioning at the 



1 'Reports on the Geology of New Jersey, Virginia,' &c. ; and especially the 'Final Report on the 

 Geology of Pennsylvania,' 1858. 



2 ' Reports on the Geology of North Carolina,' &c„ and ' American Geology,' part VI, 1857. 



