31 



ON MITRA MONTEREYI, A NEW CALIFORNIAN SPECIES. 



By Dr. S. Stillman Berry, Redlands, California. 



Read 9th January, 1920. 



The fine Mitra here described is one of several apparently unnamed 

 marine molluscs, the publication of which has been delayed by the 

 pressure of other work. 



Mitra montereyi, n.sp. 



Diagnosis. — Shell of good size, robust, heavy, spindle-shaped, 

 the maximum width contained in the length somewhat less than 

 three times; whorls only slightly convex on the spire, the latter 

 tapering quite rapidly ; sutures distinct but only weakly indented. 

 Aperture ample, its extreme measurement nearly or quite one-half 

 the entire length of the shell ; the heavy outer lip suffers moderate 

 thinning at the edge ; columellar plaits strong and primarily three, 

 but there is apt to be an incipient fourth one where the columella 

 begins to draw into the canal in front, and a small adventitious 

 plait now and then appears between two of the major ones. Canal 

 short, weakly upturned. 



Practically the entire shell sculptured by numerous, rather fine, 

 spiral threads, sometimes more or less obsolete on the peripheral 

 region, and frequently so cut by the lines of growth as to result 

 in an appearance of minute pitting, the spiral threads heaviest 

 and coarsest in the region of the canal and the front of the shell 

 generally. Lines of growth and incremental ridges numerous, 

 varying from fine to coarse and irregular. 



Entire shell covered by a strong black or very dark brown 

 periostracum. Interior of shell white or brownish white, the 

 columellar region (except the plaits) and inside of the outer lip 

 frequently deep brown. 



Measurements. 

 Length 



Type . 

 Paratype 



Type. 



66 

 60 

 49 

 30 



Cat 



5 

 0+ 



6+ 

 5 



No, 



Maximum 

 Width 

 23-5 

 22-3 

 19-1 

 12-0 



Length of 

 Aperture 

 33 • 7 mm. 

 32-2 „ 

 27-0 „ 

 17-0 „ 



Length of 

 Body-whorl 

 46-5 

 44-5 

 37-0 

 23-2 

 298 of the author's collection. 

 Type Locality. — 12 fathoms ofi Del Monte, Monterey Bay, 

 California; bottom of hard blue clay; S. S. Berry, June, 1906; 

 four specimens. 



Remarks. — Mitra montereyi is a characteristic member of the 

 orientalis-idce group. The discrepancy between shells of this species 

 and the more southern ones described as Mitra idcB by Melvill 

 (1893, p. 140) is very apparent, especially if specimens of the two 



