456 R. ETHERIDGE, JTTN., ON A LOWER- CARBONIFEROUS PRODTJCTIJS. 



1842. M. Bouchard- Chantereaux described a Devonian Productus 

 from the neighbourhood of Boulogne possessing a rudimentary area 

 and a median triangular cleft under the beak, through which the 

 author supposed a peduncle for its attachment passed *. 



1844 (1842-). Prof. L. de Koninck. It is impossible to reconcile, 

 says this eminent author, the presence of the long and delicate tubes 

 of the Producti with the idea that they could withstand the tossing 

 waves of the sea and the buffeting with a large number of rough 

 bodies, which evidently would have destroyed them. It is impro- 

 bable, he adds, that attachment took place by means of ligaments 

 issuing from these tubes or spines, according to the view formerly 

 held by M. von Buch ; neither does he think that there is sufficient 

 evidence to admit that the Producti were fixed by fibres issuing 

 along the hinge-margin of the valves. Prof, de Koninck supposes 

 that muscular fibres issued from between the free edges of the valves, 

 and so gave attachment to the shell, and in support of his view cites 

 the case of P. proboscideus, De Yern., in which he thinks the tubular 

 prolongation served to protect the fibres of attachment t- 



1845. M. de Yerneuil supported the later opinion of M. von Buch, 

 that the cardinal spines did not serve to attach the shells to submarine 

 bodies, but, he added, were probably used as channels for the introduc- 

 tion of water into the interior of the shell, necessary for its life and 

 respiration %. M. de Yerneuil considers that the Producti, with the 

 exception of those species possessing a rudimentary area and a median 

 triangular cleft (P. horrescens, P. subaculeatus, and P. productoides), 

 have the cardinal margins so tightly pressed and united along the 

 whole length of the hinge that there is neither room for an area nor 

 for a triangular cleft. With regard to those species in which the latter 

 did exist he had considerable difficulty in conceiving that it gave 

 exit to a muscle of attachment §. Of the opinions expressed by M. 

 Deshayes and Prof, de Koninck, on the one hand that the Producti 

 were free and non-adherent, and on the other that they held fast by 

 muscular fibres passing from between the free edges of the valves, 

 De Yerneuil conceived the former to be the more probable of the 

 two. Notwithstanding the peculiar prolongation of the shell in P. 

 proboscideus, which lends colour to the latter theory, the valves are 

 so united and tightly pressed along their margins that it is difficult 

 to imagine how they could have been separated by fibres during the 

 life of the mollusk ||. If the Producti were, as a rule, free shells, 

 adds M. de Yerneuil, -some, however, were attached by the apex of 

 the beak of the convex valve, as for instance P. horrescens, De Yern. 

 In this species the part in question is obliquely truncated ; and it is 

 probable that it adhered by the apex of the beak or by very short 

 fibres which issued from the base of the median aperture or cleft % 

 Finally, in a note ** to the general description of Productus, De 



* Ann. d. Sc. Nat. 2° sei\, Zoologie, xviii. p. 160. 

 t Anim. Foss. Terr. Carb. Belg. pp. 153 & 204. 



| Geol. de la Kussie d'Europe, &c, par R. I. Murchison E. de Verneuil, et 

 le Comte A. de Keyserling, ii. p. 249. 



§ Ibid. pp. 249, 250. || Ibid. p. 250. % Ibid. p. 286. ** Ibid. p. 249. 



