146 SMITHSONIAN INSTITUTION 



crimes, from which little important information can be extracted beyond one fact on which he 

 laid principal stress, and by which he said the genus was to be distinguished from Anisocrinus 

 which it approached in habitus ; this is that it had " basalia tria, parabasalia nulla," — which ir 

 current terminology means three infrabasals and no basals. He also noted that the rays and 

 arms were unequal. Wachsmuth and Springer, when redescribing the genus the following 

 year (Revision of the Palaeocrinoidea, pt. 1, p. 38), were much puzzled by the supposed fact 

 indicated by Angelin's description and figures, that this genus differed from all others of the 

 family in having but one ring of plates below the radials. We did not consider that suffi- 

 cient ground for excluding it, but expressed the opinion that the " lower ring of plates is 

 the analogue of the underbasals, and that the true basals, if not absent, are exceedingly rudi- 

 mentary " ; and added, " we take the small triangular plate which has been called the first 

 anal plate, to be the basal (subradial) on the posterior side, which is larger in the whole 

 family, and that the plates on the four other sides are very minute or only visible on the 

 inside." Considering that neither of us at that time had ever seen a specimen of Calpiocrinus, 

 this was not such a bad piece of hypothetical interpretation, as the sequel shows. 



Nine years afterward we stated that Calpiocrinus was not the aberrant genus which we 

 had supposed from Angelin's figures, but that it had the usual calyx plates of the family — 

 three underbasals and five basals. 1 This remark was based upon specimens obtained by me 

 at Dudley, England, supposed to be Calpiocrinus, but afterward described as Homalocrinus 

 dudleyensis, and now referred to the type species, H. parabasalis. Bather 2 in 1900 stated 

 that Calpiocrinus " has minute, often obsolete, IBB, but fairly large BB " ; and he separated 

 it from its former associates, Homalocrinus, Anisocrinus, etc., placing it in a family Dactyloc- 

 rinidae along with Dactylocrinus, Synerocrinus and Onychocrinus, on account of the 

 heterotomous arm structure. He placed Homalocrinus with Anisocrinus in the family 

 Taxocrinidae. 



Since taking up the study of the Crinoidea Flexibilia I have obtained some additional 

 good specimens of this type from Dudley, as well as from Gotland, and have examined a 

 fine series of Dudley specimens in the British Museum. In addition to this, Mr. Liljevall has 

 made for me careful drawings of every specimen of the two genera in the Riks Museum at 

 Stockholm, including new figures of all of Angelin's types. From all these sources of infor- 

 mation, it is possible to arrive at a satisfactory understanding of the peculiar structure of 

 these highly specialized crinoids, and it is easy now to see what has been the cause of the 

 former confusion in regard to them. 



The facts now disclosed show that Angelin's description was wrong, and that Wachsmuth 

 and Springer's interpretation of the conspicuous ring of plates was substantially correct. 

 As a matter of fact there are two rings of plates below the radials, i. e., both infrabasals and 

 basals.; but the remarkable thing about it is that the infrabasals are developed to an extent 

 and in a manner unknown in any other crinoid. The reason why the basals were not seen 

 in the specimens figured by Angelin was not so much their minuteness, or absence on the 

 exterior, as the extraordinary size of the infrabasals which concealed them from view. In 

 many dicyclic crinoids the infrabasals lie wholly within the ring of basals, abutting against 

 them only by their lateral faces ; and they are in such cases subordinate in size and position. 

 In some species they are resorbed, and entirely disappear during life. But here they overlap 

 the basals to such an extent as sometimes wholly to conceal them, and not only them, but also 

 the radials and even part of the first primibrachs. The three unequal infrabasals form a 

 relatively enormous growth, far exceeding in size the basals, and enveloping them somewhat 

 after the manner of the centrodorsal in Thiolliericrinus and in many other comatulids. The 



1 Proc. Acad. Nat. Sci. Philadelphia, Nov., 1888, p. 357. 

 " Lankester's Treatise on Zoology, pt. 3, p. 189. 



