674 



SILURIAN ENCRINITES. 



smooth. The general resemblance of the fingers to those of Cyathocrinus pinnatus of 

 Goldfuss is so great, that, were it not for the total absence of all trace of the external Jinger 

 without tentacula which Goldfuss speaks of, I should have ranked them together. 



The generic affinities of the remaining three species cannot be determined, because no part 

 of the pelvis is seen in either of them. They are placed provisionally with Actinocrinites. 

 Actinocrinites? arthriticus (nov. spec), Phil. PI. 17. f. 8. 



The anterior and external edges of the joints of all the (50 ?) fingers are boldly tuberculate. 

 Of short lateral tentacula there is a trace at b. The column was muricated. 

 Actinocrinites? expansus (nov. spec), Phil. PI. 17. f. 9. 



The arrangement of the characteristic plates of the body is unfortunately unknown. The 

 fingers ultimately amount to about 80, being unequally produced and of unequal diameter. 

 Their lateral faces of contact are flattened. The plated integument turns into the mouth after 

 the divisions of the arm amount to 20. 

 Actinocrinites? retiarius, Phil. PI. 17- f. 7* 



This is named provisionally. Its twenty plumose fingers appear to characterize it, and there 

 is no longitudinal suture in them, which easily distinguishes it from A. icosidactylus. 



DlMEROCRINITES, Phil. 



The two following species appear to me really different, generically, from Actinocrinites, 

 both by the character of the intercostal plates and the exact bifurcation of the hands and arms, 

 Though unable, at present, to characterize them completely, I propose the subgeneric name of 

 Dimerocrinites (S^tepi)?, bipartite), and have little doubt they will be eventually separated 

 from Actinocrinites. 

 Dimerocrinites decadactylus, Phil. PI. 17. f. 4. 



Intercostal plates remarkably large (as in Hypanthocrinites), and bearing on their summits 

 an interbrachial plate. Fingers ten, those of the same pair separated by a small plate at their 

 base, longitudinally sutured (i. e. composed of two rows of joints) and laterally plumose. 

 Column formed of thin joints which project in the middle. 

 Dimerocrinites icosidactylus, Phil. PI. 17- f. 5. 



The body of this must have resembled the preceding species very much. Its scapula gives 

 origin to two arms, which again bifurcate into twenty fingers, composed of two rows of joints, 

 furnished with lateral tentacula. 



Columnar joints moniliform, and near the body thin. 

 Columns of Crinoidea. PI. 18. f. 2. and f. 9. 



Nothing certain being known of the other parts of the animals to which these belong, it 

 would be premature to assign names to them 1 . 



The columnar joint, PI. 18. f. 5., may be a part of Rhodocrinites quinquangularis of Miller. 

 (N.B. From the Llandeilo Flags.) 



Besides the fourteen species noticed above, Mr. Miller describes (p. 107) Rhodocrinites 

 verus as occurring both in the transition and Mountain Limestone.' I have not had the op- 

 portunity of examining good specimens of this Encrinite, which, (contrary to Mr. Miller's 

 opinion, founded I believe on columnar joints) I venture to believe does not occur at all in 

 Mountain Limestone. There are Encrinites like it, which I have placed in a new genus in my 



1 I would here observe, however, that although displaying little to please the naturalist, the cast f. 2. PI. 18. 

 is highly characteristic of the Caradoc formation. — R. I. M. 



