RHYNCHONELLA. 95 



the 'Geology of Sussex,' 1 and although unfigured at that period, may be easily identified, 

 being a shell well known to British geologists. In 1826 Sowerby figured and described 

 the same species under the new appellation of Terebratula pisum, the same as had been 

 given some years before by Mantell to a similar shell, mentioning Hamsey as his locality ; 

 and it seems singular that the greater number of subsequent authors preferred the 

 Sowerby denomination, and it was only in 1843 that Mr. Morris, in his 'Catalogue,' 

 reestablished Mantell' s claims, by placing T. pisum as a synonym. Ter. brevirostris 

 (Rcemer, 1840) has no better claims, being identical, both in shape and character with 

 the Mantellian type. V. Buch adopts Sowerby's name, stating that the species dees 

 not appear to differ essentially from R. octoplicata of the same author ! but this will 

 require confirmation before being admitted, as the species seems to be little known to 

 continental authors, he mentions several localities. 



R. Martini abounds in the Chalk Marl and Grey Chalk of Hamsey and Folkstone, it 

 has likewise been obtained from the " Chalk detritus" of Charing (Kent) by Mr. Harris; and 

 some rare individuals have also been discovered in the Upper Green Sand of Horningsham, 

 near Warminster, associated with another small species, which has since been termed Rh. 

 Grasiana by M. d'Orbigny ; the last-named shell seems to differ from the true R. Martini 

 by its greater breadth and gibbosity, as well as by the frontal margin of the ventral valve 

 greatly indenting that of the dorsal one. Mr. S. P. Woodward seems inclined to consider 

 R. Grasiana as the adult state of R. Martini an opinion which may perhaps prove 

 to be correct, but which I do not yet consider sufficiently demonstrated, from never 

 observing among the numerous examples of R. Martini, found at Hamsey and Folkstone, 

 specimens presenting the characters assigned to R. Grasiana : it may, therefore, for 

 the present, be desirable to describe both separately ; but if future observers should 

 decide on the two being considered as one, then M. d'Orbigny's name will require to be 

 placed as the synonym, on account of Mantell's priority, and it is but just to observe that, 

 while proposing his name, R. Grasiana, the distinguished French Palaeontologist did not 

 omit to remark that, " perhaps his species is the T. pisum of Sow., but which he was unable 

 to affirm, on account of the differences which he remarks between his specimens and those 

 figured by Sowerby" ('Pal. Franc' Ter. Cret., vol. iv., p. 38) ; but, although fully admitting 

 the difficulty, still specimens of the true R. Martini, perfectly agreeing with the figures 

 published by Sowerby of T. pisum, occur in France, and have been collected more than 

 once, both by M. Bouchard and myself, at Cap Blanc Nez, near Calais. 



1 Page 131, "Ter. Martini, subscrotiform, longitudinally striated, margin finely serrated; both valves 

 slightly depressed in front, beaks very small. This is a minute and delicate species, scarcely 0'3 inch 

 either in length or width ; each valve is marked with upwards of 30 longitudinal striae, and both 

 equally convex. The margin is finely serrated by the terminations of the striae, and is nearly straight 

 in front, the sides are not waved, as in the last species (T. sulcata), named after W. Martin. Locality — 

 Hamsey." 



13 



