ORDOVICIAN AND SILURIAN BRACHIOPODA OF THE GIRVAN DISTRICT. 897 



is indicated by the limitation of the cardinal crenulations to a portion of the hinge- 

 line, and the internal characters agree in a general manner with Str. (Br.) varistriata 

 (Conrad)* and Str. (Br.) profunda (Hall),t of the American Silurian. 



Stropheodonta (Brachyprion) Walmstedti (Lindstrom). 

 (Plate XVII, fig. 3.) 



I860. Strophomeha Walmstedti, Lindstrom. Proc. Roy. Acad. Stockholm, pi. xiii, fig. 16. 



1868. Strophomena Walmstedti, Lindstrom, Davidson, Trans. Geol. Soc. Glasyow, vol. i, p. 18, pi. iii, 



figs. 5, 6. 

 1870. Strophomena Walmstedti, Lindstrom, Davidson, \lon. Brit. Foss. Brack., vol. iii, pt. vii, p. 290, 



pi. xl, figs. 6-8. 

 1883. Strophomena Walmstedti, Lindstrom, Davidson, ibid., vol. v, Silur. Suppl., p. 226. 



This species is recorded by Davidson \ from the Wenlock Shale of the Pentland Hills 

 and from the Upper Llandovery of Cuddystone Glen, Girvan. The two specimens 

 from the latter locality in Mrs Gray's collection labelled by Davidson are poor ; one is 

 the internal cast of a pedicle-valve, measuring about 40 mm. in length, and shows ob- 

 scurely the muscle-scars and pittings and coarse oblique denticulations on the hinge-line 

 close to the beak which were not mentioned or depicted by Davidson but are typical of 

 the subgenus. A specimen from Penkill occurs in the Hunterian collection at Glasgow. 



Horizons. — (l) Camregan Group ; (2) Penkill Group. 



Localities. — (l) Cuddystone Glen ; (2) Penkill. 



Stropheodonta (Brachyprion) sp. 

 (Plate XVII, fig. 20.) 



Shell transversely semicircular, widest along hinge-line ; cardinal angles slightly 

 alate and pointed at about 45°-60°. Pedicle-valve gently convex, lateral portions 

 somewhat flattened ; beak small, acute ; hinge-area narrow, triangular, transversely 

 striated, steeply inclined to plane of valve, with triangular delthyrium ; hinge-plates 

 semioval near delthyrium, elongate, extending for a short distance along hinge-line 

 close to beak, marked with 12-14 transverse oblique parallel straight grooves; 

 remainder of hinge-line not denticulate. Diductor scars large, flabelliform, indistinct, 

 very weakly impressed. Surface ornamentation unknown. 



Dimensions. — Length about 12 mm. ; width about 24 mm. 



Horizon. -Camregan Group. 



Locality. Camregan Wood. 



Re marks. -The more transverse shape of this shell and the apparent absence of 

 the coarse radial ornamentation distinguish this imperfectly known shell from Str. 

 columbana. Only two internal casts of the pedicle-valve are known, so that the 

 material is quite insufficient for a satisfactory comparison. 



* Conrad, Journ. Acad. Sc. Philadelphia, viii, 1842, p. 255, pi. 14, fig. (;. 

 t Hall, Palxont. New York, vol. ii, 1852, p. 61, pi. 21, figs. 4, 5. 

 % Davidson, op. cit., vol. iii, p. 290, pi. xl, figs. 6-8. 



