36 Mr. F. A. Bather on British Fossil Crinoids : 



to the true meaning of the ventral sac, to assert that they ai'e 

 of no morphological importance. 



The large size of the posterior infra-basal, caused by its 

 rising up to meet the radianal, is noteworthy, especially in 

 connexion with the possible Carabocrinid affinities of this 

 genus. 



In this species the angle which the side of the cup makes 

 Avith the long axis is not 9|°, as erroneously stated on p. 225, 

 but is 15° 15'. 



1 take this opportunity of publishing better representations 

 of the British Museum specimens 57478 a (PI. I. fig. 2) and 

 57478 h (PI. I. fig. 1) ; these correspond to figures 3 and 5 

 of plate X. ('Annals,' 1890, vol. vi.). 



B. Thenarocrinus gracilis, sp. nov. 



This species is founded on a specimen in the general collec- 

 tion of the Museum of the Yorkshire Literary and Pliiloso- 

 phical Society at York. Although I saw this specimen when 

 examining the Crinoids of that museum in September 1889, 

 yet, as the genus Thenarocrinus was not then formulated, the 

 relationship of this species to 7\ callipygus escaped my notice. 

 Unfortunately the existence of this specimen only recurred to 

 me after Paper III. had gone to press. It is with little doubt 

 a Thenarocrinus, and, being entrusted to me through the 

 kindness of my friend Mr. H. M. Platnauer, Secretary to the 

 Yorkshire Literary and Philosophical Society, I hasten to 

 describe it. It would have been better to have procured yet 

 other specimens, but none are known to me, and it seems 

 advantageous to publish a description while on the subject of 

 Thenarocrinus, instead of laying it aside to be again forgotten. 



The specimen (PI. I. fig. 4) is a crown with 6 millim. of 

 stem attached ; it lies in the matrix, but is fortunately seen 

 from the posterior. Formerly in the possession of Mr. Edward 

 "Wood, of Kichmond, Yorkshire, it was in 1880 bought along 

 with the rest of that gentleman's specimens by John Reed, 

 Esq., M.R.C.S., of York, and by him presented with the 

 whole of his collection to the Literary and Philosophical 

 Society. 



The specimen retains Mr. Wood's original label, which 

 runs as follows : — " Cyathocrinus [showiiig Proboscis), Silu- 

 rian, Dudleyy It obviously comes from the Upper Wen- 

 lock Limestone. 



Diagnosis. 

 Cup conical, rather elongate ; plates mostly higher than 



