ON SOME PELMATOZOA FROM THE CHAZY LIME- 

 STONE OF NEW YORK 



BY 



GEORGE HENRY HUDSON 



In some material from Valcour island, Lake Champlain, given 

 by me to Mr Percy E. Raymond in 1902 he was so fortunate as 

 to find a fragment of Blastidocrinus carchariae- 

 d e n s Bill, with two of the large deltoid interambulacral plates 

 in position and showing much of the internal structure of an 

 ambulacrum [pi. 5 fig. j]. In 1903, while examining some exca- 

 vated material from the same locality (which the writer had left 

 out to weather), Dr C. E. Beecher found a small fragment of a 

 crushed individual which showed a pair of the plates I have 

 called bibrachials, nearly in their proper relation to the great 

 deltoids. In 1904 the writer found two bibrachials joined along 

 their common suture, and these are figured on plate 4 at L. 

 While gathering up some of the remaining portions of the same 

 weathered stratum in 1905, Erastus M. Hudson obtained the 

 most complete specimen of this species yet found. From this 

 material and from about a thousand separate plates kindly 

 assembled for me by Miss Ada M. Carpenter from the unas- 

 sorted collections of some years, and representing over 186 

 different individuals, as shown by that number of apical pieces, 

 I have made the following more complete description of this 

 interesting species, 



Blastoidocrinus carchariaedens Billings 

 Can. Org. Rem. Decade IV. 1859. p. 18, pi. i, fig. la-is 



Plates 1-7, text figures 1—3 



General description. Theca large, in some specimens attaining 

 a hight of 36 mm and a width of more than 40 mm, pentagonal, 

 clearly separated into an oral and aboral surface with the greatest 

 width at the boundary. 



Aboral portion of theca deeply invaginated, appearing in a 

 side view as a low, inverted, truncate cone whose otiter walls 



