254 Prof. J. Miiller on the Structure of the Echinoderms. 



assuredly allied with ours; but we should not be justified in 

 identifying the two either from the description or the figure. 



In the Royal Mineralogical Museum of this place there is a 

 model in plaster of an English Crinoid from Dudley, the exces- 

 sively delicate and numerous rays of whose arms, and the regular 

 series of their articulations transversely and longitudinally, pre- 

 sent a certain similarity with the network of the Swedish Crinoid. 

 The calyx agrees with that of Cyathocrinus rugosiLS, Miill., i. e. 

 Crotalocrinv^ rugosv^, Austen, having the same sculpture of the 

 calycine plates. At the first sight of this model, which came 

 from M. Crantz, one is inclined to ascribe to this English Cri- 

 noid the same reticulated structure of the hands as in the Swe- 

 dish form, and to regard them both as species of one and the 

 same genus, or of two closely allied genera. On careful exami- 

 nation, however, no certain evidence of a transverse connexion of 

 the joints in the English Crinoid can be obtained. In fact, the 

 very numerous series of articulations are so given off from the 

 calyx, that there are great difficulties in the way of the sup- 

 position that they are united into five hands. However, this 

 point can only be decided by the examination of various original 

 and well-preserved specimens. 



Austen thus speaks of Crotalocrirms in the ' Annals of Natural 

 History,' vol. xi. 1843, p. 198: — '^ Dorso-central plates five; 

 first series of perisomic plates five; second series five; on the 

 latter are a series of wedge-shaped plates which bear the rays : 

 the exact number of these plates is unascertained. Column with 

 a pentapetalous perforation. 



" C. rugosus. The plates surrounding the body agree with 

 the generic character. Kays numerous, probably amounting to 

 one hundred. Column composed of thin joints articulating into 

 each other by radiating strise. The columnar canal is pentape- 

 talous. The rays are remarkably small in proportion to the size 

 of the animal." 



The authors, who could compare with Miller's specimen, ob- 

 serve, that Miller has erred with regard to the plates, which he 

 wrongly regards as scapulae, with a single excavation for articu- 

 lation with the arm-joints. These plates possessed no excavation 

 at all, but a regular series of wedge-shaped plates rested upon 

 them, from which the rays, amounting to about 100, proceed. 



The description which M'Coy gives of the genus Crotalocrinus 

 and of C. rugosus in his ' Synopsis of the Classification of the 

 British Palaeozoic Rocks,' pt. 2. p. 55, strengthens my belief that 

 the model of the English Crinoid is referable to C. rugosus. The 

 description of the calycine plates agrees exactly. It is stated 

 with regard to the five scapulae that a series of small pentagonal 

 plates rests upon each, which for the whole breadth of each 



