FOSSILS OF THE NIAOABA GROUP. 429 



SUPPLEMENTARY NOTES. 



The following notes are mainly in reference to species described in a 

 paper by Profs. Alexander Winchell and Oliver Marct, published in 

 Vol. 1, No. 1, of the Memoirs of the Boston Society of Natural History, 

 entitled "An Enumeration of Fossils collected in the Niagara Limestone 

 at Chicago, Illinois." 



Holocystites, Hall. 



(Page 353.) 



I had overlooked the fact that the name Holocystis had been proposed 

 by Lonsdale for a genus of corals. The difference of the terminal 

 syllable has in many cases been regarded as a sufficient distinction, and 

 is perhaps preferable to adopting a new name. Should it be objected to, 

 however, 1 propose the name Megacystites. 



ICHTHYOCRINUS SUBANGULARIS, HaLL. 



(Page 367.) 



The following figure, fro in a specimen kindly loaned me by Prof. 

 Marcy, and which I suppose to have been used in the description of 

 /. corhis, shows the form and arrangement of the plates of the base and 

 and lower parts of the rays, diflering in no essential 

 particular from specimens I have identified with I. 

 subangiilaris.* The suture lines of this specimen had 

 been marked with pencil, previous to coming into my 

 hands, and it shows distinctly the series of three radial 

 plates as well as siihradials. The specimen from which 

 my description and figure of /. suhangidaris was made (Plate xi, fig. 15, 

 of this paper), is from Bridgeport. It preserves the substance of the 

 plates, and is more fit for comparison of external characters than internal 

 casts alone. 



Besides the specimen used for the diagram, there is, in the collection 

 of Prof. Marcy, another one which equally shows the structure of the 



* The basal plates proper of Ichthtocbinits have heretofore been shown by me to be undeveloped 

 externally, or are covered by the summit of the column ; and the lower plates, shown on the 

 exterior of the calyx, are properly subradials, the basals being too minute for representation. 



