232 Reviews — F. Springer— Cleiocriniis. 



or Ichthyocrinidee {sensu latiore). The composition of the cup was 

 unknown, but was seen to be peculiar ; by careful dissection and 

 preparation of specimens belonging to the Geological Survey of 

 Canada, Mr. Springer has now been able to show that it consists of 

 5 infrabasals, 5 basals, and 5 radials, followed by a large sei-ies 

 of fixed brachials and piniiulars, as well as by a vertical series of 

 anals resting on the posterior basal. The peculiarity lies in the 

 facts that the basal and radial circlets have been pushed down over 

 the infrabasal circlet and top of the stem, and that in this process 

 the radials have been separated, while the basals have been pushed 

 up between them so as to support the first primibrachs on their 

 shoulders. Mr. Springer also shows that the arms are pinnulate, 

 a fact mentioned by Billings in obscure fashion but hitherto over- 

 looked ; and he states that the angles of both stem and lumen are 

 interradial, instead of alternating as is the case in later crinoids. 

 The conclusion of his most interesting research is "that Cleiocriniis 

 is evidently an intermediate form between the Camerata and the 

 Flexibilia," and in this respect he associates it with Reteocrimis. 

 His precise intention, however, is not clear, and since he "looks 

 for enlightenment" to phylogenists on this side of the Atlantic, 

 a few suggestions may be welcome. The word "intermediate " can 

 hardly be meant to imply either that the Camerata were evolved from 

 the Flexibilia by way of Cleiocriniis, etc., or vice versa. The pinnulate 

 stage of arm-structure found in Cleiocrinns was not approached by 

 Flexibilia until the Carboniferous Epoch ; on the other hand, the 

 infrabasal circlet, in its complete retention of pentamerism, is more 

 primitive than that of any known Flexibilia. Whatever be the 

 origin of Cleiocriniis, we must therefore suppose that the Ichthyo- 

 crinoid character of direct lateral union of the arms has been 

 independently acquired and no more proves a relationship to the 

 Flexibilia than it does to the still more similar Uintacrinns. The 

 composition of the cup and of the arms would allow us to place 

 Cleiocriniis with the dicyclic Camerata or Inadunata; but pinnulation 

 was not attained by any Inadunate crinoid before the Middle or 

 Upper Silurian, while the lateral union of the arms is opposed to 

 the general trend of Inadunate evolution. Therefore it seems most 

 simple to place Cleiocriniis with the Dicyclic Camei'ata, from known 

 representatives of which it differs in the suppression of inter- 

 brachials. On this ground it is necessary to erect for it a fourth 

 family, Cleioceinid^, contemporaneous in its first appearance with 

 Eeteocrinidge and Ehodocrinidee, but, unlike them, producing no 

 descendants. The structure of the base remains without precedent 

 and, with our present knowledge, inexplicable; but it is hard to 

 believe that the angular shape of the lower margins of the radials 

 is reminiscent of their former position above the basals : is it not 

 rather a downward prolongation such as we find in Pentacrinus 

 (= Extracrinus) ? The only approach to the structure in other 

 respects is the familiar invagination of the base, as seen in the 

 contemporary Archaocrinns, and the most probable hypothesis seems 

 to be that the base of Cleiocriniis is an exaggeration of this type. 



