E. ETHERIDGE, JUN., ON LOWEE-CAEBONIEEEOTJS INVERTEBEATA. 11 



them to Mr. T. Davidson, E.R.S., who was kind enough to favour 

 me with the following reply to my letter : — " As you say, one or 

 two of them look like a small variety of L. squamiformis. This 

 last is, however, a much larger shell ; and I would almost feel in- 

 clined to refer them to L. mytiloides" The present individuals so 

 closely resemble those, that, although they are in any thing but a 

 good state of preservation, I do not hesitate to refer them to the 

 same species. 



Log. and Horizon. In hardened shale, quarry under Craiglockhart 

 Hill, as before ; in shale with other marine fossils at Woodhall 

 Mill, as before ; in shale above the sandstone at Craigleith Quarry, 

 near Edinburgh. 



Class PELECYPODA (LAMELLIBBANCHIATA). 



Genus Avictjla, Klein. 



Avicitla Hendeesoni, sp. nov. PI. I. fig. 11. 



Sp. char. Obliquely transversely elongated, very inequilateral. 

 Anterior end well marked, divided off by the byssal sinus ; posterior 

 end produced, obtusely rounded ; posterior wing flattened, falciform ; 

 hinge-line straight, not so long as the shell ; ventral margin sub- 

 parallel with the hinge-line, indented by the byssal notch, otherwise 

 convex. Posterior slope well marked, obtusely rounded; byssal 

 sinus extending from the beak as a pronounced groove in each valve ; 

 widening towards the ventral margin. Umbones anterior, promi- 

 nent. Surface of both the body of the shell and the posterior wing 

 covered with very regular concentric imbricating striae. 



Obs. Avicula Hendersoni is closely allied to several Irish species 

 figured by Prof. M'Coy *, and seems to be nearest to his A. angusta, 

 but with the dorsal and ventral margins much more nearly parallel 

 than in the latter, in this respect corresponding more closely with 

 A. recta, M'Coy, and A. gibbosa, M'Coy, from which, however, it 

 otherwise differs considerably. I name the species after Mr. Hen- 

 derson, to whom I am indebted for the loan of the majority of the 

 specimens described in this communication. 



Loc. and Horizon. In a hard Cyprid shale, quarry on the north 

 side of the Colinton road, under Craiglockhart Hill, near Edinburgh, 

 near the base of the Cement-stone group ; in shale with marine fos- 

 sils at Woodhall, as before. 



Genus Avictjlopecten-, M'Coy. 

 Aviculojjecten, M'Coy, 1851, Ann. & Mag. Nat. Hist. vii. p. 171. 



Attcuxopecten-, sp. 



Obs. A portion of one valve has been obtained from the Woodhall 

 Shale, It is a radiately striated species, with the ribs crossed by 



* Synop. Carb. Foss. Ireland, t. xiii. f. 20, 



