CRICK : SPECIES OF NATTTILUS FROM THE INFERIOR OOLITE. 



119 



The same specimen exhibits also the 'black-layer' as a band enveloping 

 the whorl immediately in front of the aperture, its greatest width 

 (7-5 mm.) being at the middle of the periphery. 



The largest specimen (No. C. 4503) has the last two septa much 

 nearer together than the rest, and is probably an adult shell. 



The peristome is well shown in the specimen No. C. 3177. This 

 example is more robust than the others, but as all the specimens 

 are from the same horizon and locality, this diiference is probably 

 merely sexual, the more robust form being the male, the others 

 females. In the shell of the female the aperture is oval and the 



Fig. II. — Nautilus Bradfordensis, n sp. a, lateral riew of au example of the more 

 inflated form, showing the 'hlack-layer ' immediately in front of the aperture, 

 and the fine line indicating the course of the anterior boundary of the muscular 

 scar and of the annulus ; a portion of the test on the body-chamber is represented 

 as having been broken away, in order to depict this line, which really exists on the 

 opposite side of the fossil, b, front view ot the same. Inferior Oolite {concavus- 

 zone) : Bradford Abbas, Dorset. Drawn from a specimen in the British Museum 

 Collection [C. 3177J. About five-sixths natural size. 



periphery convex, while the aperture of the shell of the male is 

 relatively wider, and the periphery somewhat depressed of even 

 slightly concave. 



Affinities. — Compared with N. lineatus,^ the present species is 

 a smaller, more rapidly increasing shell, with deeper chambers, and 

 more inflated sides. 



Sowerby, Min. Conch., vol. i (1813), p. 89, pi. xli. The specimen figured as 

 Nautilus lineatus by Mr. Foord and the present writer in Ann. & Mag. Nat. 

 Hist., ser. vi, vol. v (1890), p. 276, fig. 8, and by Mr. Foord in Cat. Foss. 

 Ceph. British Museum, pt. ii (1891), p. 212, fig. 41, is really the specimen 

 which we regarded as the type of N. pseudollncatus. 



