392 TWENTIETH REPORT ON THE STATE CABINET. 



communicated by Prof. Marcy ; nor do I conceive it possible that any 

 species, with the structure given, exists in these rocks. Prof. Winchell 

 speaks of "the large size of the basal plates, correspondig to the sides 

 "instead of the angles of the pentagonal base," pa. 89; and yet, on page 

 108, in distinguishing it from /. suh angular is, he remarks, that "besides 

 "the uniform want of angularity of this species," etc., which character he 

 had previously admitted. Now the basal plates of this genus are very 

 minute, and the subradials, usually regarded as basal plates, are like- 

 wise quite small, and can only be described as of "large size" by uniting 

 with them the first radials, which would necessarily leave two radials above. 



Lecanocrinus pusillus, W. and M., pa. 90. Specimens communicated by 

 Prof. Marcy, which correspond in form and proportions with the descrip- 

 tion of this species, belong to the Genus Cyathocrinus or Poteriocri- 

 NUS, and are identical with the species I have described as Cyathocrinus 

 pusillus, referred to on page 324 (20) of this paper, and which differs very 

 little from Poteriocrinus yisiformis from the same horizon in Tennessee. 



Strophomejia macra^ W. and M., pa. 91, is Stroplioviena {Strophodonta) 

 semifasciata, Hall, Transactions of the Albany Institute, Vol. iv. A 

 comparison of the interior and exterior of specimens from Waldron, 

 Indiana, leaves no room for specific distinction. I have not obtained this 

 species from Wisconsin. 



Strophomena 7iiagarensis, W. and M., pa. 92. A comparison of nume- 

 rous specimens of Strophomena profunda with the specimen communicated 

 by Prof. Winchell, afi'ords no means for specific distinction. In the speci- 

 men of <S. profunda, figured on pi. 13 (4), the lithographer has taken 

 some liberties in the representation of the muscular impression, which 

 define it too strongly, and render it a little too short ; while in the figure 

 of Prof. Winchell, it is too strongly limited on its anterior border, and 

 proportionally too narrow for the specimen. 



Streptorhynchus hemiaster, W. and M., pa. 93, is a young individual of 

 Streptorhyiichus suhplaiia, Conrad sp. 



Pentamerus chicagoensis, W. and M., pa. 94, is represented with five 

 plications on each side ; while the specimen shows two strong ones in the 

 centre, a much smaller one adjacent on the side ; and outside of this a broad 

 low elevation, while the third one is not defined by any depression between 

 it and the margin of the shell. The specimen is quite imperfect, but I am 

 inclined to believe it will prove only an extravagant form of P. ventricosus. 



Pleurotomaria gonopleura, W. and M., pa. 98. This species does not 

 resemble P. hoyi, Hall, but is the same which I have compared with 

 Murchisonia hercyna, Billings (page 345 (41) ), which it much resembles. 



