E. ETHERIDGE, JUN., ON A LOWER-CARBONIFEROUS PRODUCTUS. 457 



Yerneuil adds that the tubes or spines cotild not in the least have 

 served to attach the shell. 



1846. Count A. von Keyserling appears to have believed that the 

 Producti lived with their convex or ventral valves downwards, a 

 position which would be assumed by an example if thrown into 

 water, divested of matrix, and filled with a material having the same 

 specific weight as water *. 



1847. Prof. L. de Koninck, in criticising M. de Yerneuil's theory 

 as to the admission of water through the tubes or spines, thinks that, 

 had they been intended for so important an office, it is probable that 

 their distribution over the valves of the shell would not have been 

 left so much to chance — in other words, that the distribution would 

 have been on a more defined plan f. The views expressed by M. de 

 Yerneuil on the theory of M. Bouchard-Chantereaux are acquiesced 

 in ; and Prof, de Koninck further believes that the latter writer in- 

 cluded in his Productus certain forms which should have been placed 

 in Leptama. The learned author is unable to reconcile a free and 

 unattached habit (as supposed by M. Deshayes and others) with the 

 possession of long and delicate tubes by the majority of the species. 

 He believes that in the Producti, with the exception of P. prohosci- 

 deus and its allies P. JVystianus and P. genuinus, the fibres of attach- 

 ment issued from between the free margins of the valves. The 

 truncated apex of the beak in P. horrescens is regarded, not as caused 

 by the attachment of the shell directly to submarine bodies by the 

 beak, but by friction of the same part against the rock to which the 

 animal was attached by its fibres J. 



1848. Prof. H. B. Geinitz figures an example of Orthotrix Gold- 

 fussi, Miinster ( = Strophalosia, King), from the Lower Zechstein of 

 Milbitz near Gera, which is distinctly represented with some of its 

 hinge-spines encircling and clinging to a spine of Productus Jior- 

 ridus §. On the succeeding plate he gives a restoration of P. lior- 

 ridus, Sow., suspended by its fibres of attachment passing from 

 between the valves j|. 



1850. M. A. d'Orbigny supposed that the Producti rested on sea- 

 bottoms of fine sediment with their convex or ventral valves down- 

 wards, held in that position by the long spines, which he compared 

 to those of Spondylus striatus and other shells. The mode of 

 attachment of P. horridus he regarded as exceptional, and the pro- 

 boscis-like prolongation of P. proboscideus as a deformity due to an 

 accidentally constrained position of the shell in holes or crevices of 

 rock during life, the edges of the mantle being prolonged upwards 

 so as to reach the surface of the ground %. 



* Reise in das Petschora-Land im Jahre 1843, pp. 198, 199. 



t Monograpbie du genre Productus, Mem. Soc. Royale des Sc. de Liege, iv. 

 pp. 104, 112-114; Recb. sur les Anim. Foss., Mon. des Genres Prodtictus et 

 Chonetes, p. 15. 



+ Ibid. pp. 21, 22. 



| Die Yersteinerungen des deutschen Zecbstemgebirges, pi. 2. fig. 2<, b, c. 



j| T. 6. f. 1- 



f Ann. des Sc. Nat. ser. 3, adii. (Zoologie) p. 314. 



