SPIRIFERA. 15 



and Kirkby, have proven to my entire satisfaction that the hinge-line was at times shorter 

 than the greatest width, nor was the shell always so extremely transverse (PI. I, figs. 24, 

 25, 30) as is commonly the case with full-grown individuals (PI. I, figs. 23, 27) ; but I 

 feel less certain regarding Professor King's figs. 21 and 23. The distinctive characters of 

 Sp. Permiana have not, in my humble opinion, been sufficiently established to warrant 

 the present adoption of that species. 1 



Sp. alata is distinguished from Sp. laminosa of the Carboniferous period, which it 

 sometimes resembles by its more transverse shape. 



The largest British specimen I have been able to examine measured 14 lines in length, 

 32 in breadth, and 11 in depth. 



T. alata is not a very common species in England. It has been found at Tunstall 

 and Humbleton Hill, Midderidge and Tynemouth Cliff. On the Continent it occurs at 

 Possneck, Ropsen, &c. ; Bell-Sound, Spitzberg. (De Koninck.) 



Spirifera ? Clannyana, King. Plate I, figs. 47 — 49. 



Martinia Clannyana, King. Catalogue of the Organic Remains of the Permian Rocks 

 of Northumberland and Durham, 19th August, 1848; and 

 Monograph of English Permian Fossils, p. 134, pi. x, 

 figs. 11—13, 1850. 

 — Winchiana? King. Catalogue, p. 8; and Monograph, p. 135, pi. x, 

 figs. 14—17. 



This small shell is almost circular, and sometimes slightly emarginate in front; as 

 wide, or a little wider, than long; valves unequally convex; hinge-line shorter than the 



1 Professor King believes his species well characterised, and kindly forwarded for my inspection the 

 young example, fig. 23 of his plate ; but Sowerby's drawing is not very correct, for the specimen is much 

 more regularly semicircular, and possesses seven ribs, comprising the mesial one. It measures — length 1^, 

 width 2\, depth 1^ lines, and might perhaps be the fry of Sp. alata ? 



Professor King diagnoses his Sp. Permiana — " Margin semi-elliptical, twice as wide as long. Lateral 

 surfaces with four or more sharpish, rather distant ribs ; mesial furrow or ridge not much larger than the 

 adjoining folds. Beak erect in casts, but gibbous in testiferous specimens ; valves marked with regular 

 lamellae of growth, crossed with hair-like striae, rarely exceeding half an inch in length ; differs from Trigo- 

 nostrata undulata in having a narrower mesial furrow or elevation, and only half the number of folds, 

 which are broader and more angulated than those of the latter ; the valves are not so tumid, and the lateral 

 extremities are rounded instead of pointed." My figs. 35 and 36, PI. I, approach most to Professor 

 King's Sp. Permiana. 



Spirifer Schrenkii, Keyserling, described and illustrated in Dr. A. G. Schrenk's excellent work, 

 ' Reise nach dem Pordosten des Europbischen Russlands durcU die Tundren der Samogeden,' vol. i, p. 88, 

 1848; and vol. ii, p. 106, pi. hi, figs. 20 — 30, 1854, appears to be closely related to Spirifera alata, 

 but is well distinguished by the absence of the rib which exists in the sinus of the ventral valve of 

 Schlotheiui's species. 



