430 MB. L. EICHAEDSON & MR. J. I". WALKEK [Nov. T907, 



' couches a Eudesia cardium ' from Sowerby's 0. ornithocephcda, and 

 has called them Zeilleria ranvilliana. 1 



Ornithella ounithocephala (Sowerbv, pars). (PL XXVIII. figs. 

 5 a & 5 b.) 



1812. 'Mineral Conchology ' vol. i, p. 227 & pi. ci, fig. 2. 



1851. Davidson, ' Monogr. Brit. Foss. Brach.' (Palaeont. Soc.) vol. i, pt. iii, p. 40 & 



pi. vii, figs. 6, 9, 12. 

 1878. Id. Suppl. vol. iv, p. 167, pi. xxii, fig. 2 & pi. xxiv, fig. 27. 

 1884. E. Deslongchamps, in A. d'Orbigny's Paleontologie Francaise : Terrain 



Jnrassiqne — Brachiopodes,' p. 303 & pi. lxxxvii. 



Diagnosis. — Shell oval, elongated, longer than wide, the greatest 

 width being near the centre of the shell, from which it gradually 

 slopes towards the anterior margin, which is generally more truncate 

 in adult specimens and more rounded in young. The shell is in- 

 flated, and somewhat swollen at the umbo of the dorsal valve. The 

 greatest thickness of the shell is near the centre, from which the 

 surface slopes towards the lateral and anterior margins. The beak of 

 the ventral valve tapers, and is suddenly recurved, nearly touching 

 the umbo of the dorsal valve. The beak- ridges are very slightly 

 concave. The foramen is small and round. Shell-surface smooth. 



Remarks. — In this species the young shells are more inflated 

 and globose, and more rounded at the anterior margin, than the 

 adult. As the shell grows the length appears to increase more than 

 the breadth, and it becomes thinner towards the margin. The 

 anterior margin becomes more truncate, and sometimes bilobate. 



This species differs from Ornithella cadomensis (E. Desl.) in not 

 being depressed near the umbo of the dorsal valve, in 

 not showing well-marked lamella?, in having its beak-ridges less 

 concave, in the beak nearly touching the dorsal valve, and in the 

 hinge-line being less straight. It is, however, difficult to separate 

 some specimens. 2 



Hhynchonella voltjta, 3 sp. nov. (PL XXVIII, figs. 7 a & 7 b.) 



T.l. Farmcombe Quarry, near Doulting (Somerset). 

 H. Fullers' Earth (Knorri-Cl&y*). 



V- 



■Colin. L. Richardson. 



Diagnosis. — Shell wider than long, asymmetrical, being dis- 

 placed or twisted so as to divide the shell into two approximately- 

 equal parts — the front of one half of the shell being more elevated 

 than the other. The shell is ornamented by strong, well-developed 

 ribs. The ventral valve is twisted, so as to be divided into two 



1 In d'Orbigny's ' Paleontologie Franchise : Terrain Jurassique — Brachio- 

 podes' 1885, p. 426. 



2 In the MS. submitted to my colleague for revision, he inserted the following 

 sentence : — ' The Fullers'- Earth specimens will require a new name, as Sowerby's 

 shell is from the Cornbrash. I should like to call it Ornithella fullonensis.' 

 His sudden death prevented me from discussing the matter ; but, until I have 

 seen more Cornbrash forms, I prefer to reserve an opinion, and employ the old 

 name. — L. E. 



3 Latin, volutus, a, urn, twisted. 



