REPORT ON THE CRINOIDEA. 153 



notions of morphology. I freely admit the functional analogy of the under-basals of 

 Encrinus, JErisocrinus, &c., with the central plate of Cupressocrinus or Stemviatocrinus ; 

 but until the apparently simple nature of the latter shall have been proved to be really 

 due to the disappearance of sutures, as in the basal ring of Bathycrinus, Rhizocrinus, and 

 Agassizocrinus, I think that we must regard it as a top stem-joint, corresponding to what 

 de Loriol calls the " article basal " in Aioiocrinus and Millericrinus. 



Encrinus is remarkable as being the only Neocrinoid with ten (or twenty) arms of 

 biserial joints, which increases its resemblance to Stemmatocrinus. There are, however, 

 some species (Encrinus gracilis) with ten uniserial arms, as in the other Neocrinoids and 

 in Erisocrinus so far as yet known. This is also the case in de Koninck's genus 

 Philocrinus from the Carboniferous strata of the Punjaub.^ But the basals seem to be 

 much higher and the cup generally deeper than in either Erisocrinus or Stemmatocrinus. 

 The structure of the lower part of the cup was unfortunately obscured in de Koninck's 

 specimen, so that the presence of under-basals is still doubtful. 



Wachsmuth and Springer point out that the absence of any anal plates in Erisocrinus 

 and Stemmatocrinus, and the want of any knowledge of their ventral side render it 

 doubtful " whether they belong to the Cyathocrinidae, or even to the Pateocrinoidea ; and 

 if it had not been for their marked resemblance to Eupachycrinus, in which a ventral 

 tube has been observed, and that both were representatives of the same geological age, 

 living under the very same conditions, we should have felt strongly disposed to place the 

 whole genus with Encrinus, with which it has, indeed, both in body and arms, the 

 closest affinities." ^ They think the number of radials to be not of material, or, at most, 

 " only of generic importance ; but in Encrinus the aboral side of the body, or the plates 

 which in all Cyathocrinidse constitute the calyx, form almost a flat disk — at least do 

 not extend beyond the basal plane — and this is the only distinction which can be 

 discovered between the two forms in the fossil state. This, however, may involve 

 important structural modification in the internal anatomy of the animal, and probably 

 shut out Encrinus entirely from the Pateocrinoidea." 



Our knowledge of the anatomy of recent Crinoids, however, does not favour this 

 supposition. There is very much less difi'erence between the calices of Encrinus and 

 Erisocrinus than between that of Antedon eschrichti with high radials and a narrow but 

 deep central funnel, and the low flattened calyx of any Actinometra. But the only 

 difference exhibited by the ventral sides of these two types is that the mouth is central 

 in the Antedon and excentric in Actinometra. I can therefore see no reason for 

 supposing that Erisocrinus had a solid inflexible vault built up of the so-called oral plates, 

 like that of the CyathocrinidES, with which family it, as well as Stemmatocrinus, is placed 



1 Description of some Fossils from India, discovered by Dr. A. Fleming of Edinburgh, Quart. Journ. Geol. Soc, 

 vol. xix. p. 4, pi. ii. fig. 5. 



2 Revision, part i. p. 142. 



(ZOOL. CHALL. EXP. — PART XX.XII. — 1884.) ^^ -^ 



