OCT 24 1917 V 



Atf,-™,-.* 



THE 



GEOLOGICAL MAGAZINE 



NEW SERIES. DECADE VI. VOL. IV 



So. X.— OCTOBER, 1917. 



0^tI<3-I]Sr^^Ili ARTICLES. 



I. — Morphological Studies on the Echinoidea Holectypoida and 



their Allies. 



By Herbert L. Hawkins, M.Sc, F.G.S., Lecturer in Geology, University 

 College, Beading. 



YI. The Buccal Armature of Conulus albogaleeus, Leske, 



(PLATE XXVIII.) 



1 . Introduction. 



SINCE 1824, when Charles Stokes transmitted to the Geological 

 Society a drawing of the "buccal plates" of Conulus, the 

 question of the existence and characters of the lantern in that genus 

 has been intermittently, but inconclusively, debated. The course of 

 this discussion may be briefly outlined here. 



Desmoulins, in 1835, was of the opinion that the structures 

 figured by Stokes were either jaws or teeth, but was uncertain as to 

 which parts of the lantern-apparatus they might represent. Desor, 

 in 1842, seems to have regarded these buccal plates as being the 

 distal ends of the p} : ramids, being unaware that they were superficial 

 structures with no inward prolongation. Forbes, in 1850, gave 

 a figure of the "jaws and teeth", and in spite of the peculiar and 

 improbable nature of these structures as depicted in his figure, 

 echinologists of such experience as d'Orbigny and Wright accepted 

 the drawings as representing genuine traces of the lantern. All the 

 writers above mentioned were convinced that Conulus was a gnatho- 

 stomatous form, basing their belief chiefly on a very reasonable 

 analogy with other Echinoids in which the peristome is centrally 

 placed. It is surprising that there is no record of any serious 

 attempt at excavation of the interior of a specimen during the first 

 fifty years of uncertainty. There is little difficulty in making 

 preparations of the inner surface of the test of an Echinoid from the 

 Upper Chalk, but the genius of a comparative anatomist was needed 

 to demonstrate that fossils have in sides no less than Recent forms. 



Loven and Duncan more or less simultaneously applied their 

 energies to the elucidation of the detailed internal anatomy of fossil 

 Echinoids, and, curiously enough, came to diametrically opposite 

 conclusions as to the perignathic structures of Conulus. Loven 

 figured the perignathic girdle, and, while admitting the non-discovery 

 of jaws, expressed his conviction that such organs were present. 

 Duncan denied that there was a perignathic girdle in Conulus, at 



DECADE VI. — VOL. IV. — NO. X. 28 



Z/3 



