Mr. T. Stock on Kammplatten. 253 



XXVI. — Farther Observations on Kammplatten^ and Note 

 on Ctenoptychius pectinatns, Ag. By TilOMAS Stock, 

 Xatural-Iiistory Department, Museum of Science and 



Art, Edinbur.a-li*. 



[Plate VIII. fio's. 1-4 «.] 



Mr. T. p. Barkas, F.G.S., lias, with great kindness, allowed 

 me to examine the entire series of Kammplatten contained in 

 his cabinet. Three of them are of interest, and deserve careful 

 description. 



No. 6t (Plate VIII, fig. 1, nat. size, and fig. 1 a, twice nat, 

 size). Length 11 lines ; originally it was somewhat longer. 

 Lamella 4 lines, greatest breadth 2 lines ; convex on the upper 

 surface, concave on the lower. The pectination is very fine. 

 Along the middle line there is a series of about eighteen 

 minute punctures. The handle is noticeable for its great rela- 

 tive length ; along two thirds of its course it is directed to- 

 Avards the pectinated edge of the lamella ; it then bends away 

 from it at a very obtuse angle till it is cut oflf by the edge of 

 the slab. Its exposed margin is fringed by a very narrow 

 and slightly raised border (see PI. VIII. fig. 1 a), which, when 

 examined by the lens, is seen to be broken up into a series of 

 coarse denticulations, which pass at intervals into more or less 

 prolonged ridges. There ore dubious traces of a border on the 

 opposite margin, seen in the matrix where the extremity has 

 been broken away. 



Horizon. Low-Main seam, Coal-measures, Northumber- 

 land. 



Locality. Newsham. 



Collection of Mr. T. P. Barkas, F.G.S. 



No. 7 (PI. VIII. fig. 2, nat. size, and fig. 2 a, twice nat. 

 size). Length 4 lines; greatest diameter of the lamella 

 1 line. The lamella is pectinated along the lower two thirds 

 of its margin ; the denticles are about seventeen in number ; 

 they are the marginal prolongations of striaj, whose origin can 

 be traced back to an indistinct ridge which is continuous with 

 that of the handle to be described. The strice and their den- 

 ticular terminations all take a parallel but distinctly oblique 

 direction. The handle (see PI. VIII. fig. 2 a) is short (1^ line), 



* The first part of tliis communication was read before the Ediuburfh 

 Geological (Society, Jan. 19, 1882. 



t The numbers are continuous with those of the preceding paper on 

 the same subject, ' Annals/ Aug. 188], p. 95. 



