﻿TUODUCTUS. 



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two or three such specimens, one of which (fig. 2) will be found represented in our plate ; 

 but at Ferques, near Boulogne-sur-mer, in France, the shell is often found in a very complete 

 state of preservation. It differs, also, from P. aculeatus by the presence of a narrow hinge- 

 area, first noticed by M. Bouchard-Chantereaux from specimens found at Ferques, 1 Some 

 palaeontologists have supposed that Strophalosia {Ort/iis) productoides of Murchison might 

 be a synonym of the shell under description, and Prof. L. dc Koninck has suggested that 

 P. subacnleat/ts might possibly be a constant and well-marked variety of Strophalosia pro- 

 ductoides, but I believe both forms to be not only specifically distinct, but that they belong 

 to a distinct section of the genns Productus, i. e. Strophalosia, King. P. subaculeatus 

 varies considerably in the number of spines which are scattered over the surface of its 

 ventral valve. Tn some examples they are much nearer to each other than in other indi- 

 viduals, and Prof. M'Coy observes that the young specimens rarely show any of the 

 obsolete concentric wrinkles, and in them also the spine-bases are more nearly round ; 

 that " they are fewer, more distant, and less regular than in P. spiuulosus (Sow.), and the 

 peculiar form of the tubercles, their number, and tuberculatum of the ventral valve, as 

 well as a less gibbosity, separate it from P. aculeatus." In none of the British specimens 

 I have been able to see were the spines in place, but some of the French examples still 

 preserved their spines, which were slender, and sometimes exceeding half an inch in 

 length; some may even have attained an inch, and many of our British examples of 

 P. subaculeatus have exceeded in dimensions those I have seen from the Continent. I 

 have not been able to obtain any British or foreign specimen in which the interior of the 

 valves could be studied, but examples of the dorsal valve showing the cardinal process 

 have been figured by M. Bouchard. 



Locality. In England, P. subaculeatus is common in the Middle Devonian Limestone 

 of Woolborough quarry, near Newton Abbot ; at Barton, Lummaton, and Hope's Nose, 

 near Torquay ; and Plymouth. But 1 have seen no examples from any of our Upper 

 Devonian beds, where it ought to have occurred, but it is stated by Prof. M'Coy and 

 Mr. Salter to have been found abundantly in the Upper Devonian beds of Petherwin and 

 Landlake, in Cornwall. 



On the Continent it is abundant at Ferques, in the Bas Boulonnais ; at Gahard, in 

 Brittany (M. Rouault) ; also at Chimay and Couvin, in Belgium; also in the Eifel; at 

 Zadosk, on the Don ; and in the neighbourhood of Voronege, in Russia. I have described 

 and figured it from China ; and it occurs likewise in America, &c. 2 



1 "Note sur le Genre Productus ;" ' Annates des Sciences Naturelles,' Sept., 1842. 



2 In the fourth vol., 2nd series, of the 'Bulletin de la Soc. Geol. de France' (1847), M. de Verneuil 

 remarks, " Productus subacideatus, Murch. (Stroptiomena lacrymosa, Conrad) ; a small species proper to 

 the Devonian system, and -which has never been found lower down. In America, it appears for the 

 first time, in the Corniferous Limestone of Charleston Landing and Lewis's Creek (Indiana), where it is 

 associated with the fine fish described by Mr. Norwood, under the name of Macropetalichthys rapheidolalis : 

 it is found to go through all the Devonian stages, such as those of Hamilton, Portage, and Chemung. 



