Geol.— Vol. II.] ANDERSON— CRETACEOUS DEPOSITS. *J*J 



CEPHALOPODA 



NAUTILOIDEA 

 12. Nautilus gabbi, sp. no v. 



Nautilus texanus (?) (Shum.) Gabb, Pal. Cal., Vol. I, p. 59, PI. IX. 



There is in N. gabbi about the same number of septa that Stoliczka states 

 commonly occurs with A^. kayeaniis; the umbilicus is similarly small, though 

 not closed, the position of the siphuncle is subcentral, a little nearer the base 

 of the septa, and the ornamentation of the shell is the same in so far as the 

 flexuous radial markings are concerned. There is the same backward curve 

 upon the ventral surface. Small specimens of the Shasta species show in 

 addition to this some fine revolving striae that give a beautiful cross-hatched 

 sculpture that is not seen in any of the older specimens. 



This species of A^autilus,\Y\nch. Gabb doubtfully referred 

 to the Texan species, has recently been collected upon Cot- 

 tonwood Creek, by Dr. J. P. Smith. It agrees in all respects 

 with Gabb's figures, and it seems probable that it was from 

 one of the specimens obtained from Shasta County that the 

 figures were made. Gabb reports the species also from 

 Mount Diablo, but the identity of the two species ought to 

 be accepted with hesitation. It resembles in some respects 

 JV. campbellt Meek from Comox, Vancouver Island, and 

 might be mistaken for this species. 



Nautilus gabbi \% closely related to N. kayeaniis Stol. from 

 the Ootatoor beds of Southern India. Stoliczka considers 

 his species a representative of a group of associated forms, 

 one of which he identifies with N. fscudo-clegans d'Orbigny. 



Occurrence. — Nautilus gabbi is found in the Upper 

 Horsetown beds of Shasta Count}', California, though its 

 range has not yet been ascertained. 



Two specimens of a Nautilus labeled " Claytons, Contra 

 Costa County" are among the Pioche collection at the 

 University of California. They apparently belong to a 

 distinct species, in which the umbilicus is entirely covered 

 by a thick callous, and which has a characteristic ornamen- 

 tation of surface. The dark coloration is preserved upon 



