46 BRITISH PERMIAN BRACHIOPODA. 



few short ones occasionally occurred seems demonstrated from their presence in a certain 

 number of specimens recently discovered at Ryhope by Mr. Kirkby (fig. 42). Numerous 

 lines laminae, or wrinkles of growth, occasionally occur on the surface of both valves, and 

 particularly so in specimens from certain localities in the lower Zechstein, where the shell 

 assumed dwarfish dimensions, and lived under different conditions to those that existed 

 during the deposition of the upper shell limestone. 1 



Interiorly the valves articulate by means of teeth and sockets ; and as the muscular 

 and reniform impressions agree in arrangement and character with those of St. Goldfussi, 

 already described, they need not be again reproduced (figs. 37 and 39). 



In dimensions this species does not often appear to exceed 15 or 16 lines in 

 length, by about the same in breadth, the greatest depth between the valves rarely 

 exceeding 6 lines. 



Considerable difference of opinion has been expressed regarding the shells here classed 

 under Orlhotrix lamellosus, of Geinitz, a species founded on a dwarf race, of which 

 Strophalosia Morrisiana, var. Humbletonensis, may be considered the full grown and 

 most favoured form. Geinitz's shell (of which I have seen several typical examples, found 

 near Gera by Mr. Howse, as well as others from Moderwitz, &c., forwarded by Baron 

 Schauroth) never appears to have greatly exceeded 7 or 8 lines in length and breadth ; and 

 they also very often exhibit indications of having adhered by portions of their beak, but 

 otherwise possess all the essential or important characters of the more favoured varieties, 

 for their larger valve is sparingly covered with long adpressed spines, and more or less 

 distinctly marked radiating striae. The smaller valve also is generally spineless, but 

 striated as in the more perfect shells ; but in this dwarf race or condition the surfaces of 

 both valves seems more closely marked with larger and more prominent incremental lines, 

 or laminose projections, than in the var. Humbletonensis, King. While describing his 

 Strophalosia Morrisiana, in p. 100 of the • Monograph of English Permian Fossils/ 

 Professor King places Orthotrix lamellosus with a point of doubt among the synonyms 

 of his species, and adds — " In making the Orthotrix lamellosus of Geinitz synonymous 

 with this species, notwithstanding the former is stated to be without spines on the small 

 valve, I have been influenced by certain of my specimens displaying lamella on this valve, 

 somewhat similar to those represented in the ' Versteinerungen,' at figs. 1 5 a, 16, 17 «, 21, 

 pi. v. The fossils identified by Dr. Geinitz ( vide pi. vi, figs. 16 — 18) with the Stroph. 



1 It may be remembered that Professor King, in p. 101 of his 'Monograph,' has alluded to a singular 

 peculiarity presented by some examples found at Humbleton hill, of appearing possessed of three valves, a 

 circumstance he feels at a loss to account for satisfactorily. Mr. Howse (in his paper published in the 

 ' Annals ' for 1857) remarks, "there is also a tendency in this species to form a new internal surface 

 behind the old upper valve, for the purpose of contracting the interior of the shell. It is not an additional 

 third valve as King has supposed, for it is essentially connected with the upper valve, and must have been 

 formed by the upper lobe of the mantle." I have seen several examples presenting this peculiarity, but it 

 is only of rare occurrence, and is therefore not a general character of the species. 



