" A Blastoid found in the Devonian Rocks of Ontario/' Canadian 

 Naturalist, vol. x. no. 2. 



t American Journal of Science, July l>60 f p. 229. 

 X Geol. Survey of Illinois, vol, v. p/-464. 



\ 



230 Messrs. R. Etheridge, Jun., and P. H, Carpenter on 



We are inclined to believe that this is really the case, as 

 does Montgomery *, the latest writer on the subject ; but we 

 must take exception to the manner in which lie compares 

 Eleacrimts to Pentremites. The "situation of the anal orifice " 

 in the former type is in no way peculiar, but perfectly normal ; 

 and it has nothing whatever to do with the presence of an 

 extra interradial in the hinder interambulacrum, although 

 this is obviously due to the existence of the anal plate. Mr. 

 Montgomery also says that " in Pentremites, in which the 

 lateral opening is completely wanting, there is of course no 

 anal plate." This statement sounds rather strange to any 

 one acquainted with Homer's careful description of the 

 manner in which the large anal spiracle is divided into a i 



median (anal) and two lateral openings. 



Eleacrinns, like various other Blastoids, has been described 

 as possessing a dicyclic base. Lyon believed himself to have 

 discovered that below the pieces which Romer described as 

 basals there are three yet smaller ones, separating them from 

 the top stem-joint, and also interradial in position. In ac- 

 cordance with his peculiar system of nomenclature, he trans- 

 ferred the name " basals " to these plates, and called the 

 basals of Romer " primary radials," although they are only 

 three in number and are not situated in the direction of the 

 rays ; while the fork-pieces or true radials were called primary 

 radials, second series. Hall made no mention of the plates 

 termed basals by Lyon, though they were redescribed by 

 Billings f, who corrected the errors in Lyon's terminology. 

 Zittel says nothing about them, however; and they are also 

 left without notice by Montgomery. As in the cases of Pen- 

 tremites and OrophocriniiS) we can only say that we have 



never seen them, but do not deny their existence and are 

 open to conviction. 



We would remark, however, that if the plates of the lower 

 series (supposing them to exist) are interradial, as the upper 

 ones are, they can be in no way homologous with the under- 

 basals of the Crinoids ; for these alternate with the basals 

 proper (subradials or parabasals of the old nomenclature), as 

 has been already pointed out by Meek and Worthen \. In 

 fact the existence of two successive series of interradial plates 

 between the stem and the radials would be such an anoma- 

 lous feature in the morphology of the Pelmatozoa, and, in- 















