Walker — Greensand Brachiopoda, 401 



from the middle of the shell to the front margin, by its valves (espe- 

 cially the dorsal) being more convex, and by the sides of the shell 

 being more rounded. From W. tamarindus it differs by its more 

 elongated form, and Mr. Meyer informs me that its loop resembles 

 that of W. Morrisii. 



Terebr alula Meyeri, sp. n. PI. XIX. Fig. 6.— Shell somewhat 

 ovate, inflated, greatest thickness near the middle of the shell. 

 Shell -surface smooth, strongly marked by concentric lines of 

 growth, beak short, incurved and depressed, truncated by a large 

 foramen, whose transverse diameter is generally the greater. The 

 foramen is separated from the hinge line by a wide but shallow 

 deltidium in one piece ; beak ridges inconspicuous. Ventral valve 

 increasing regularly in convexity from its sides to its centre. Dorsal 

 valve increasing in convexity both from its sides and also from the 

 beak and front margin nearly to the central point of the shell. 

 Both valves slightly taper towards the front margin ; which, in some 

 specimens, is almost straight, giving the shell a slightly pentagonal 

 form. This last character is more marked in some specimens than in 

 others ; the front margin is slightly flexuous and not plicated ; loop 

 short. Dimensions: length, 1*42 inches; breadth, "96 inches; 

 thickness, -83 inches. This shell is readily distinguished by its 

 shape from other Cretaceous Terebratulce. I have dedicated this 

 species in compliment to C. J. A. Meyer, Esq., who has added 

 much to our knowledge of Cretaceous Brachiopoda. 



Terehratula microtrema, sp. n., PL XIX. Figs. 7 and 8. — Shell 

 somewhat ovate, widest towards the frontal margin, much com- 

 pressed at the sides. Beak ridges rounded, beak short, truncated 

 by a large foramen ; separated from the hinge line by a wide but very 

 shallow deltidium in one piece; ventral valve slightly convex to- 

 wards the beak, becoming flattened towards the front margin, much 

 compressed at the sides ; dorsal valve slightly convex near the beak, 

 sides somewhat flattened. Frontal margin more or less plicated, the 

 ventral valve having an elevation on each side of the centre, inter- 

 locking with the ventral depression or furrow of the dorsal valve. 

 These elevations and depressions are sometimes nearly wanting, so 

 that the frontal margin is only a little undulated. In most adult 

 specimens the plications become greatly developed, deeply interlock- 

 ing ; and the front of the ventral valve shows a strong central ridge 

 with a shallow furrow on each side of it. Loop short. Shell struc- 

 ture very peculiar, having but very few and small perforations, 

 (Woodcut, Fig. 3.) Dimensions; length, 1 "17 inches; width, -83 ; 

 thickness varies from '625 to '75 inches. 



The plicated specimens approach nearest to T. prmlonga; from 

 which, however, the species may be at once distinguished by its 

 peculiar shell-structure. It is also more compressed at the sides, the 

 foramen is more approximated to the hinge line, and the beak is shorter. 

 It is well distinguished from T. bipUcata by its shell structure and 

 general shape. The forms in which the plications are less conspicu- 

 ous approach most nearly in appearance to T. extensa, but they 

 differ from that species in shell structure, in being wider, and in the 



