Mr. F. A. Bather on British Fossil Crinoids. 373 



in front than behind, very obtusely angular at the sides, more 

 finely sculptured than the head, very delicately bat densely 

 rugose, and finely punctured ; the punctures are small but 

 distinct, and separated from each other by about three dia- 

 meters of a puncture, at the sides they are indistinct ; the 

 lateral fovea is small and round. There are no basal im- 

 pressions. The elytra are less shining than the thorax, very 

 finely coriaceous, with very closely-placed, minute, shining 

 dots or granules ; the stria3 are fine, and in them some very 

 fine punctures may be seen. The metasternum is shining, 

 with an interrupted median impressed line, slightly curved 

 down anteriorly, and then more obliquely declivous, the front 

 part rather dull, rather closely asperate-punctate and pilose, 

 with an indication of a small angular tuberosity in the middle. 

 The anterior femora have a small tooth rather beyond the 

 middle. $ . 



This species is allied to G. hilaris, Hope, but the thorax 

 is more narrowed at the base, &c. 



XLVIII. — British Fossil Crinoids. 

 By F. A. Bather, M.A., F.G.S. 



II. The Classification of the Tnadunata Fistulata 

 (continued from p. 334). 



[Plate XV.] 



Differential Characters. 

 C. The Arms. 



We have now to consider the value of Arm-characters in 

 classification. Here the main principles are so simple and 

 so generally acknowledged that their discussion need not 

 detain us long. They are as follows : — 



The simplest form of arm consists of a series of ossicles 

 continuing the line of the Radial ; the joint-faces of the ossicles 

 are parallel to one another, and there are no pinnules. This, 

 it is fairly obvious, must also be the most primitive form of 

 arm : examples are, Hybocrinus, TIoplocri?ius } and Baero- 

 crimes (PI. XV. figs, la, b). 



Nearly as simple would be an arm splitting in two, on the 

 2nd or 3rd costal as axillare, and of which each half should 

 resemble the preceding type : such arms are not indeed found 

 in any known Fistulata, but they represent a stage through 



