R. ETHERIDGE ON ADHERENT CARBONIFEROUS PRODUCITDJE. 503 



Turning to Strophalosia we observe that the hinge-line is pro- 

 portionately shorter than in Fig. 4 ; the area is, again, different in 

 form, and there are, so far as we know, no hinge-spines in Strophalosia, 

 although the presence or absence of hinge-spines has been treated 

 by Mr. Davidson as a character not of generic importance*. Still 

 where, as in the present instance (Fig. 4), we are precluded from 

 using the characters of either the muscular or reniform impressions, 

 or even the cardinal process, we must seize upon those exhibited, 

 however trivial. There is, notwithstanding, this resemblance with 

 Strophalosia — a species of the latter has been shown by Geinitz to 

 be adherent by its spines. 



Lastly, we have to take into consideration Productella. This 

 genus, or subgenus, was established by Prof. Hall for Devonian 

 species of Productus with a narrow hinge-area, small teeth and 

 sockets, and reniform vascular impressions resembling those of 

 Aulostegesf. The linear hinge-area and foramen visible in Fig. 4 

 might as well represent those of Productella as of Chonetes, especially 

 as we have no conclusive evidence of a pseudo-deltidium. Produc- 

 tella possessed spines along the hinge-line, as in Productus, but not 

 on the upper edge of the area, as in Chonetes ; and, further, the 

 presence of spines in Fig. 4, radiating from the body of the 

 shell, again indicates a closer alliance with Productella than 

 with Chonetes. 



In conclusion, I think, from the evidence afforded by the specimen 

 from which Figs 2 & 3 are taken, we may venture to assume the 

 former existence of another member of the Productida?, exclusive of 

 Productus and Strophalosia, which, either during the whole of its 

 existence or some part of it (we do not know which), lived adhering 

 to foreign bodies by its spines and some portion of its shell, and that 

 fair evidence exists of the probability of this form being re- 

 ferable to the genus Chonetes. Fig. 4 may or may not be a Chonetes ; 

 my friend Mr. T. Davidson, F.R.S., is inclined to regard it rather as 

 a Productus. As the state of preservation is not so satisfactory as it 

 might be, it will perhaps be better to leave it an open question for 

 the present. Is it a Productella ? 



As to the habit of Chonetes, Prof, de Koninck believes that, in 

 the young state, short and fine fibres issued from the fissure, by 

 means of which attachment took place, the shell becoming free only 

 at an advanced stage of its existence J. He is supported in this 

 view by M. de Yerneuil, who appears to follow de Koninck very 

 closely in his views as to Chonetes §. 



Although I have examined a large number of well-preserved 

 specimens of Chonetes Laguessiana, De Koninck, I have never suc- 

 ceeded in detecting oblique tubes traversing the area in connexion 



* Introduction to Brit. Foss. Braeh. p. 114. 

 t Pal. N. York, iv. p. 150. 

 \ Anim. Foss. Tert. Carb. Belgique, p. 208. 

 § Geology of Russia, ii. Pakeontol. p. 239. 



