CRICK : SPECIES OF NATJTILIfS EEOM THE INEEEIOE OOLITE. 



137 



the central position of the siphuncle ; it probably was, when complete, 

 quite as large as the broad form. 



The larger specimen (C. 4499) exhibits the impression of the deep 

 hyponomic sinus of the aperture. 



Affinities and Differences. — This species is closely allied to N. Smithi,^ 

 but careful comparison with the type of that species shows that the 

 present species increases less rapidly, and has a larger umbilicus than 

 that species. In I^. exterebratus- the whorl is more quadrate in section, 

 the umbilicus smaller, and the test without longitudinal ornaments 

 and nearly smooth. 



Fig. XIV. — Nautilus semiornatus, n.sp. Front view of an example of the less 

 inflated form. Inferior Oolite : Bradford Abbas, Dorset. Drawn from 

 a specimen in the British Museum Collection [C. 3244]. About two-thirds 

 natural size. 



Form, and Zoo. — Inferior Oolite [concavus-zone) : Bradford Abbas. 

 Both specimens are labelled ^^ concavum - zoyie, Bradford Abbas." 

 Mr. Buckman, after a careful examination of the matrix of the 

 specimens, considers No. C. 4499 to be from the " concavum-zone 

 (probably Hi/perlioceras-'beds), Bradford Abbas," and No. C. 3244 

 from the "fossil-bed of Bradford Abbas (probably upper part with 

 Syperlioceras).''^ 



IL I^AUTiLus ExiGuus, n.sp. Fig. XY. 



Ty^es.— British Museum Coll., Nos. C. 4233 and C. 4235. 



Specific Characters. — Shell small, rather rapidly increasing, narrowly 

 nmbilicated ; greatest thickness at the umbilical margin, about 

 two-thirds of the diameter of the shell ; height of outer whorl about 

 four-sevenths of the diameter of the shell. Whorls few, exact number 



1 Foord & Crick: Ann. & Mag. Nat. Hist., ser. vi, vol. v (1890), p. 287, fig. 16. 

 - Vide supra, p. 130, 



