ctuck: species of nautilus from the inferior oolite. 1127 



23 mm.; ditto above preceding whorl, about 19 mm.; thickness, 

 23 mm.; width of umbilicus, 5 mm.; distance of centre of siphuncle 

 from periphery, 6 mm. The dimensions of the latter are : — Diameter, 

 50 mm. ; height of outer whorl, 28 mm. ; ditto above preceding whorl, 

 about 23 mm. ; thickness, 28 mm. ; width of umbilicus, 7 mm. ; distance 

 of centre of siphuncle from periphery, 7 mm. The example No. 67,909 

 agTees with the younger portion of the specimen 'No. C. 4229, and this 

 in its turn agrees with the inner portion of the example No. C. 4495. 

 Tlie surface of the shell is reticulated up to the point at which it 

 attains a diameter of about 32 mm. ; after that it is ornamented only 

 with longitudinal striae, which are confined to the peripheral area. 

 The young shells are more compressed than those of iV. ornatus ^ and 

 N. Burtonensis,- and they also lack the slightly sulcated periphery of 

 the latter. 



Sowerby's name W. .nmcafus being preoccupied by Fichtel, D'Orbigny 

 altered it to J^. suhsinuatus. 



Affinities and Differences. — This species is closely allied to N. crassi- 

 sinuatus, which is next to be described, and its different points will be 

 alluded to under that species. 



Form, and Loc. — Inferior Oolite : Dundry. [No. 67,909.] Inferior 

 Oolite ("probably Truellei^ - hed.^^ — S. S. Buckman) : Halfway 

 House, near Sherborne, Dorset. [No. C. 4229.] Inferior Oolite 

 C TF'itchellia-'heds — bottom part of 'fossil-bed' of Sandford Lane, 

 or just below that — matrix." — S. S. Buckman): near Sherborne, 

 Dorset. [No. C. 4495.] 



Sowerby states that the type, for which he was indebted to 

 Mr. Parkinson, "was found somewhere near Yeovil, but Mr. Parkinson 

 is not acq^uainted with the exact locality." 



5. Nautilus crassisinuatus, n.sp. Fig. VIIT. 



Specific Characters. — Shell compressed, somewhat rapidly increasing ; 

 greatest thickness close to the umbilicus, rather more than one-half of 

 the diameter of the shell; height of outer whorl about three-fifths of 

 the diameter of the shell. Whorls three or four ; inclusion nearly com- 

 plete, about three -fourths in the outer whorl ; umbilicus small, about 

 one-tenth or one-eleventh of the diameter of the shell in width, with 

 subangular margin and somewhat convex slightly overhanging sides. 

 Whorl trapezoidal in section, rather higher than wide, indented to 

 about one-fourth of its height by the preceding whorl; periphery 

 broadly rounded ; sides flattened, feebly convex ; inner area very 

 distinct, somewhat convex, feebly overhanging. Length of body- 

 chamber not seen. Chambers not very deep, their depth measured 

 at the periphery not quite one-half of the corresponding height of 

 the whorl ; suture-line with a deep sinus on the lateral area having 



1 Foord & CricV: Ann. & Mag. Nat. Hist., ser. vi, vol. v (1890), p. 273, fig. 7. 



• Foord & Crick, torn, cit., p. 288, fig. 17. 



3 Mr. Buckman says the Truellei-heAB of Halfway House are called tlie ' fossil-bed.' 



VOL. III.- — DECEMBER, 1898. 9 



