714 



ME. T T. GEOOM ON PELANECH1NUS COEALLINUS. 



(b) Gemmiform from the oral surface, probably long-stemmed 



(fig. 2). 



(c) Large tridactyle, spoon-tipped, from the aboral surface 

 (fig. 3). ' • 



Pech cellar ia-stems. Long, slender, head without constriction 

 (fig. 4). 



EXPLANATION OF PLATE XXVIII. 



Fig. 1, a, b, c, d. Pedicellarise from round the peristome, X50. e. Internal view 

 of one of the valves, X 50. /. Internal view of an older one (dia- 

 grammatic), X 50. g. Basal view of one, X 50. 



2, Slender pedicellaria from oral surface, X 50. 



3, a. Large tridactyle pedicellaria from aboral surface, seen from above. 



X40. b, Ditto, seen from the side; c, view of basal end; d, view of 

 distal end. 



4, a, b, c, d. Pedicellaria-stalks, X 50. 



Discussion. 



Prof. Duncan said he had recently gone over Mr. Keeping's 

 drawings, and his interpretation of the peristomial plates resembled 

 Mr. Groom's. The imbricating plates are all ambulacral, there 

 being no interradial plates of that nature as in Cidaris. The dis- 

 covery of fossil pedicellarise was quite new. 



