New Species from Lou-er Cai-hoiiiferoiis of Bally castle. 23 



deltidiuiu. Chilidium of two triangular flaps resting against the 

 quadrifid cardinal process. 



The interior of the brachial valve shows a rather characteristic 

 pair of radial ridges (PI. Ill, Fig. 4c, and Text-fig. 1, A), beside 

 the median ridge (M), which marks presumably the inner margins of 

 the fcnterior adductor scars. The brachial ridges (B) are only well 

 marked at their proximal extremities. 



FKt. 1. — Diagram to show position of ridges in the brachial valve of Chonctrs 

 clcgans, sp. nov. C, cardinal process ; H, hinge plate ; B, brachial ridge ; 

 A, ridge marking inner margin of adductor scar ; M, median ridge. 



Holoti/2)e. — A specimen Avith only the exterior of the pedicle 

 valve free of matrix, in the collection of the Geological Survey 

 of Ireland. 



Locality. — Very abundant in the shales associated with the main 

 limestone at North Star Colliery, H miles east of Ballycastle. 



Comparisons. — This species agrees very well with pi. xlvii, fig. 12, 

 of Davidson's Mon. Brit. Carb. Brach., except in the shape of the 

 cardinal extremities, which is more like that of fig. 16 of the 

 same plate. 



Specimens recorded as Ch. laguessiana from the Lower Limestone 

 of Scotland (Scot. Surv. Coll. 213),^ agree with the present form in 

 all respects, except the proportion showing a ventral sulcus, which 

 was 16 in 32. 



The Ch. cf. hardrensis of the Acre Limestone (D.j), Northumber- 

 land, is agam practically the same. In twelve specimens ^ the only 

 differences from the Ballycastle form were that only two had any 

 trace of a ventral sulcus, and the number of cardinal spines was 

 Lisually six or seven on each side, only one having eight. 



A somewhat similar, if not identical, form is figured and briefly 

 described by Vaughan ^ from D.,-, of Gower. 



' I was enabled to inspect these through the kindness of Dr. G. \V. Lee. 

 ^ Kindly lent me by Dr. Stanley Smith. 



^ Dixon and Yaughan, "The Carboniferous Succession in Gower": 

 Q.J.G.S., vol. Ixvii, 1911, p. 561, and pi. xli, figs. 3rt, 36. 



