40 BRITISH PERMIAN BRACHIOPODA. 



convex pseudo-deltidiura. There is also a small area in the dorsal valve. The ventral 

 or dental valve is moderately convex, with or without a shallow mesial furrow or sinus ; 

 the dorsal or socket one being moderately concave, and following the curves of the opposite 

 valve, that is to say, with or without a slight mesial elevation corresponding with the sinus 

 in the ventral valve. Externally the whole surface (areas excepted) is covered with a 

 multitude of curved slender tubular spines, which attain a considerable length, and are 

 irregularly placed at not much more than their thickness one from the other (fig. 13). 

 These spines in the larger valve lie, from their origin, either close to the surface, or vertically 

 implanted, become suddenly bent downwards so as to become entangled one with the 

 other ; l but those on the smaller valve seem in general to converge towards the centre of 

 the shell, 8 the valves being likewise marked by numerous incremental lines or wrinkles of 

 growth. When quite young the shell is much depressed, the smaller valve being almost 

 flat and circular, while the umbone is comparatively produced. Strophalosia Goldfussi 

 varies also in proportions, but does not often exceed 1 inch in length, and somewhat less 

 in width ; but when covered with its spinulose appendages, presented larger proportions. 



In the interior of the larger valve a tooth is situated on each side at the base of the 

 deltidium, which articulates by the means of sockets placed on both sides of a cardinal 

 process in the opposite valve (fig, 12) ; and at a small distance from the extremity of the 

 beak there is a short, raised, slightly curved platform, with a somewhat obtuse abrupt 

 termination towards the centre of the valve. On this are placed the two small oval scars 

 produced by the adductor, and separated by a minutely elevated line or ridge (fig. 14), 

 better seen in hollow or on internal casts (figs. 10 and 13 a). Immediately under, but 

 outside, there are two longitudinal, slightly indented, and sub-quadrate semicircular 

 impressions, produced by the cardinal muscle (fig. 10 3 ), and which seem to have been 



1 M. De Koninck observes that sometimes the spines, while interlacing each other, surround foreign 

 objects which may lie within their reach, and that those situated on the beak appear to have possessed 

 that faculty in particular. He possesses specimens of which the spines envelop the fragment of a large 

 spine of Productus horridus, and Dr. Geinitz has figured another similar example. 



Mr. Howse informs me that the typical German Goldfussi from the Zechstein differ somewhat from 

 those we are accustomed to call Goldfussi in England. They are shapeless at first until well cleaned, like 

 Miinster's figure, and somewhat more circular, and densely covered with very curved spines. They occur 

 in little marly nodules, out of which they are washed with a tooth-brush, into very fine specimens. 



2 At least such is seen to be the case in many German specimens, and has been so described by 

 Professor De Koninck in his * Monographic du genre Productus.' A beautiful illustration by M. Suess 

 will be found in pi. v, fig. 10 6, of the German edition of my General Introduction. 



3 The remarkable internal cast, of which I offer an enlarged illustration in PI. Ill, figs. 9, 10, 

 was discovered by myself at Humbleton quarry, during a visit to that locality in company of Messrs. Howse 

 and Kirkby, and it is worthy of remark that, although those gentlemen and Professor King have collected 

 some hundred of specimens in the same and in other localities, as well as by Baron Schauroth in the 

 Zechstein Dolomit of Pbssneck, in Germany, in none were these scars so well or so distinctly displayed as 

 in the specimen here represented, and which I had already figured and described in my few notes on 

 Permian genera, published in vol. ii of the 'Bulletin de la Societe Linneenne de Normandie,' Feb., 1857. 



