132 



PKOCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



given above. ISTo. C. 3245 (i) is the more inflated, and C. 4498 (ii) 

 the less inflated form. They are both from Bradford Abbas. 



Affinities and Differences. — This species may be distinguished from 

 N. terehratus ^ by its smooth shell, more inflated whorls, wider and 

 flatter periphery, and the less prominent umbilical margin ; and from 

 i\^. semiornalus '^ by the more quadrate form of the transverse section 

 of its whorls, its smaller umbilicus, and the absence of longitudinal 

 ornaments. 



Form, and Log. — Inferior Oolite : Bradford Abbas, Dorset. 

 Mr. Buckman has examined both specimens : he considers No. C. 3245 

 to have come from the "fossil bed (probably concavus-hed), Bradford 

 Abbas"; and No. C. 4498 to have been derived from the " concauus- 

 zone (probably Hyperlioceras-'hed), Bradford Abbas." Judging from 

 their matrix they appear to have been obtained from the same bed. 



8. Nautilus eottjndus, n sp. Fig. XI, 



Type.—'&riti&h. Museum Coll., No. C. 3181. 



Specific Characters. — Shell more or less subglobose, with small 

 umbilicus; greatest thickness near the middle of the lateral ar«a, 

 about three-fourths of the diameter of the shell ; height of outer 



Fig. XI. — Nautilus rotundus, n.sp. a, lateral view of the type-specimen ; l, front 

 view of the same. Inferior Oolite : Sherborne, Dorset. Drawn from an 

 example in the British Museum Collection [C. 3181]. Eather more than 

 one-half natural size. 



whorl about five-ninths of the diameter of the shell. AVhorls three ; 

 inclusion nearly complete ; umbilicus small, deep, with rounded 

 margin. Whorl subtrapezoidal in transverse section, its heioht about 

 three-fourths of its width ; indented to about two-fifths of its height 



> E. Dumortier, Etudes Paleoutologiqnes sur les Depots Jurassiques du Bassin du 



Rhone, pt. iv (Lias Supcrieur), 1874, p. 42, pi. vi, figs. 1—1. 

 2 Vide infra, p. 135. 



