PRODUCTUS. 151 



The interior need hardly be described, as the details which we have carefully drawn do 

 not differ materially from those already noticed in other Producta ; so that all we require 

 to notice is that, in the ventral valve, the adductor or occlusor muscular impressions arc 

 situated almost on a level, or are longitudinally parallel, with the divaricator scars, and 

 consequently much lower in the ventral valve than in P. giganteus and some other species. 

 In the dorsal valve, the occlusor impressions arc often beautifully sculptured, and the 

 cardinal process tri-lobed. The ventral valve is more thickened than the dorsal one, and 

 possesses sometimes, though rarely, a well-defined area and fissure covered by a pseudo- 

 dcltidium, this character being beautifully displayed upon a specimen in the British 

 Museum, and of which an illustration will be found in my plate. Since several 

 palaeontologists appear, however, desirous of maintaining the term Martini as at least a 

 varietal designation, and although I cannot draw any line of distinction between the two, 

 it may be as well to mention that figs. 6 to 11 of my PI. XLIII represent the typical shapes 

 of P. Martini, while the other figures would represent P. semireticulatus. In its typical 

 condition, P. Martini may be distinguished by the great length and sometimes irregularity 

 of its anterior prolongation, the visceral portion alone being regularly arched, the shell 

 becoming afterwards suddenly bent downwards in an almost straight line, giving to some 

 specimens a peculiarly elongated and geniculated appearance, as seen in figs. 6 and 7. 

 The sudden bend of the ventral valve makes it sometimes, in the fossil state, liable to 

 fracture where the sudden bend in the valve takes place, as seen in figs. 9 and 10. The 

 lateral portions of the valve are likewise much dilated, while numerous spines, clustered 

 together, project from the auriculate portions of the valve. This is also the variety to which 

 Martin, in 1809, applied the specific denomination of Ano mites productus ; and Sowerby's P. 

 eoncinnus is evidently nothing more than a smaller form or synonym of the same. 

 Productus semireticulatus is one of the most abundant and far-spread species of the genus, 

 and is found in almost every locality where Carboniferous Brachiopoda occur. 



In England it is found in the Carboniferous Limestone and shales of Bolland, Settle, 

 Kirkby Lonsdale, Coverdale, as well as in various Derbyshire localities ; at Poolwash, in 

 the Isle of Man ; Clifton, near Bristol, &c. In Scotland, it is plentiful in Lanarkshire, 

 Renfrewshire, Ayrshire, Dumbartonshire, Stirlingshire, Eifeshire, Edinburgshire, Dum- 

 fries-shire, Peebleshire, Linlithgowshire, and Berwickshire. In Ireland, at Millecent. 

 Lisnapaste, Tankardstown, Tornaroan, Cookstown, &c. In Belgium, it occurs in the 

 lower stages of the Carboniferous Limestone of Vise, De Chokier and De Lives, near Namur, 

 and in various other localities, as well as in the Middle Limestone of Tournay. M. de 

 Koninck states he has found it likewise in the following German localities : — Crumford, at 

 Ratingen, Altwasser, &c. In Russia, M. de Verneuil and Count Keyserling obtained it in 

 several localities such as the neighbourhood ofMoscou, on the Dwina, the Oka, the Pinega, 

 and Petschora, as well as in the Timans Mountains, near the Glacial Sea, also in the Oural 

 Mountains, at Sterlitamack, &c. M. de Tchihatchef found it also in the Altai Mountains. 

 It has also been found in Spitzbergen and Australia ; in the Punjaub, and in various 



