F. R. Cowjjer Reed — Fossils from Saverfordwest. 453 



there is an internal cast of the pedicle valve of a shell which in 

 shape and other characters resembles this species, and possesses 

 muscular characters like those of the genus, especially like those of 

 the type-species H. congesta, Conr.^ The pedicle cavity, the sub- 

 parallel, short dental lamellae, and a subrhomboidal sharply bounded 

 muscular scar, angularly notched behind, and comprising the two 

 diductors enclosing the narrow contiguous adductors, are clearly 

 seen. The specimen is imperfect, but must have measured about 

 12 mm. long by 10 mm. wide. 



Locality. — Bank Saeson, Whitland. 



HoKizoN. — Slade Beds. 



MeRISTELLA Cf. CRASSA, SoW. 



Several imperfect internal casts and external impressions of 

 a species of Meristella occur in the Slade Beds near St. Martin's 

 Cemetery, Haverfordwest. In external form and internal features 

 they agree closely with M. crassa (Sow.) ^ ; in the pedicle valve we 

 find the dental lamellse pursuing the same course, and the muscular 

 area and diverging lateral vascular impressions are precisely similar; 

 in the brachial valve the cleft hinge-plate and median longitudinal 

 septum are developed in the same manner. The external shape of 

 the shell and smooth character also agree. M. a-assa occurs in the 

 Lower Llandovery, and this Slade form may prove to be a separate 

 species or a variety. 



EXPLANATION OF PLATE XXIII. 

 EiG. 1. — Trematis multistriata, sp. nov. Bracliial valve. Lower Llandeilo Lime- 

 stone : Lampeter Velfrey. x 1|. 

 ,, Iffl. — Ditto. Portion of surface of same specimen, x 15. 

 ,, 2. — Crania TurnbtMi, sp. nov. Cast of interior of upper valve. Sholeshook 



Limestone : Sholeshook railway cutting, x 1 J. 

 ,, 2a. — Ditto. Impression of part of surface of sheU of same specimen, showing 



ornamentation, x 4. 

 ,, 3. — Crania Grayi, Dav., var. Slade Beds : near St. Martin's Cemetery, 



Haverfordwest. 

 .,, 4. — Orthis {Plesiomys) porcata, McCoy, var. nov. sladensis. Cast of interior 

 of brachial valve. Slade Beds : near St. Martin's Cemetery, Haverford- 

 west. X 1\. 

 ,, 5. — Ditto. Ditto. Same horizon and locality, x 1|. 

 ,, 6. — Ditto. Cast of portion of interior of pedicle valve. Same horizon and 



locality, x 1^. 

 ,, 7. — Ditto. Impression of part of surface of shell, showing ribbing. Same 



horizon and locality, x 2. 

 ,, 8. — Orthis aff. Bouchardi, Dav. Cast of interior of brachial valve. Eedhill 



Beds : Prendergast Place, x 3. 

 ,, 9. — Ditto. Impression of part of surface, showing ribs. EedhUlBeds: road- 

 side near St. Martin's Cemetery, x 5. 

 ,, 10. — StropJiomena (?) mediocostalis, sp. nov. Cast of interior of pedicle valve. 



Slade Beds : Upper Slade. x 2. 

 ,, 10«. — Ditto. Impression of exterior of same valve and specimen, x 2. 

 ,, 11. — Ditto. Cast of interior of anterior part of brachial valve. Same horizon 



and locality, x 2J. 

 ,, 12. — Strophomena antiquata, Sow., var. Cast of interior of pedicle valve. 

 Eedhill Beds : Prendergast Place, x If. 



1 Hall & Clarke: Palseout. New York, vol. viii, Brach., pt. 2, 1894, p. 61, pi. xl, 

 figs. 23-28. 



2 Davidson : op. cit., vol. ui, p. 117, pi. siii, figs. 1-3. 



