GREY CHALK MARL. 131 



The shell is about 0-5 inch long, and 0-6 wide. The sulci are strongly 

 marked, about fifteen or sixteen on each valve, three or four occupying 

 the straight front of the margin. The beak is slightly produced, and has 

 a circular perforation. 



This species is common at Hamsey : the sulci are bolder and fewer in 

 number on the straight part of the margin, than in the other Terebratulee 

 of the chalk. 



Locahties. Hamsey, Stoneham. 



62. Terebratula Blartini. 



Subscrotiform, longitudinally striated, margin finely serrated; both 

 valves slightly dejDressed in front, beaks very small. 



This is a very minute and deUcate species, scarcely OS inch either in 

 length or width. Each valve is marked with upwards of thirty longi- 

 tudinal striae, and both are 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. 



The specific name is in commemoration of the late William Martin, 

 Esq. F.L.S. of Macclesfield, the scientific author of PetrificataDerbiensia, 

 &c. whose premature death must be deeply lamented by every friend of 

 science. 



Locahty. Hamsey. 



63. Terebratula striatula. Tab. xxv. figs. 7, 8, 12. 

 Subscrotiform, contracted at the beaks, longitudinally striated, striae 



fine, diverging ; margin acute, undulated in front, depressed on each side 

 the beak ; lower valve with a broad longitudinal sulcus. 



The length of this species is generally 0-9 inch ; the greatest width 

 07 inch ; thickness 0*4 inch. 



The upper valve is convex in the middle, and gradually slopes towards 

 the margin ; the lower valve has a sulcus along the middle. The beak is 

 slightly produced, and beneath it the margin is inflected on both sides. 

 The striae are fine, diverging from the beak to the margin ; the latter is 

 acute, and has a gentle undulation in front, produced by the dorsal 

 groove ; in the young shell this appearance is not observable. 



s 2 



