70 H. L. Hawkins — Jaw-structures in Conulus. 



V. — On the Teeth and Buccal Structures in the genes Conulus, 



Leske. 



By Herbert L. Hawkins, B.Sc, F.G.S. 

 (PLATE III.) 



THE question as to the existence and characters of the jaws in 

 Conulus albogalerus, Leske, has long been a subject of controversy. 

 On prima facie evidence it seemed probable, so long as the genus 

 was retained among the Holectypoida (the Galeritidse of older 

 authors), that jaws existed. Conulus appears as a successor to 

 Discoidea among the Cretaceous Echinoids, and, with a few excep- 

 tions, all echinologists admitted that the latter genus was armed 

 with a lantern and teeth. The truth of this assumption was proved 

 by Loven (Loven, 1892, p. 53), and the details of the jaw 

 structure were elaborated recently by myself in this Magazine 

 (pp. 148-52, PI. YI, 1909). That Conulus should be classed among the 

 Holectypoida seems to be an established proposition, and it appeared 

 in the early part of the Cretaceous period, together with Pyrina, 

 probably as an offshoot from the Holectypus line of descent. 



The history of the search for jaw -structures in Conulus shows some 

 of the most remarkable contradictory results that are to be met with 

 in the whole range of the study of fossil Echinoids. In 1829 Charles 

 Stokes, in a letter published (in extract) in the Geological Society's 

 Transactions (Stokes, 1829), announced the discovery, in ' Galerites* 

 ( Conulus) albogalerus, of structures which he called ' plates of the 

 mouth'. His figure is quite clear, and these structures (now known 

 as 'buccal plates') have been found in many specimens since that 

 time. Des Moulins, in the first of his memoirs on Echinoids 

 (Des Moulins, 1835, pp. 191 and 324), referred to Stokes' account, 

 and was undecided as to whether the structures were teeth or jaws. 

 Grateloup (1836, p. 159) classes Galerites albogalerus among those 

 species which have the ' bouche armee'. Desor expressed the opinion 

 that the structures were the extremities of jaws (Desor, 1842, p. 13), 

 and copied the figure. 



The first definite statement on the subject was made in 1850 by 

 Edward Forbes, who described and figured (Forbes, 1850, p. 3) the 

 jaws and teeth. Desor (1857, p. 181) seems to have accepted the 

 validity of this observation. The figures of the teeth are not very 

 convincing, but they were copied by d'Orbigny in the Paleontologie 

 francaise (d'Orbigny, 1859, pi. 996, figs. 9-10), and by Wright 

 (1874, pi. 1, figs. 5-6). Wright held that, the buccal plates were 

 vestiges of a true ' lantern '. Loven, in his Etudes sur les Echinoidees 

 (Loven, 1874), placed the ' Echinoconidre ' among the 'Echinoidees 

 & dents'. 



The first denial of the presence of jaws came in 1884, when 

 Duncan, in a somewhat dogmatic paper, attacked the foundation of 

 the figures and descriptions given by Forbes and Wright, and denied 

 the possibility of the existence of dentigerous jaws in Galerites 

 {Conulus) albogalerus (Duncan, 1884, p. 11). He established the fact 

 of the presence of tubercles on the outer surface of the buccal plates 

 (which seemed to preclude their derivation from any part of the 



