1914] 



Martin: New Species of Fossil Mollusca 



189 



This variety resembles very closely Chrysodomus tabulatus Baird, 

 from which it may be distinguished by its more broadly fusiform 

 character. The sculpture is the same on both varieties. Eight speci- 

 mens of C. tabulatus var. colmaensis from the Merced Series south of 

 San Francisco were constant in their broad form, and none of the 

 more slender forms, C. tabulatus Baird, were obtained from this 

 locality. The fact is considered to be sufficient reason for separation 

 of the two forms. 



CHRYSODOMUS TABULATUS BAIRD 

 Plate 20, figure 2 



Chrysodomus tabulatus Baird, Proc. Zool. Soc. of London, 1863, p. 66. 

 This species is figured to make clear the difference between it and 

 Chrysodomus tabulatus var. colmaensis, n. var. Baird 's species ap- 

 pears to be quite constant in its size and general characters. It dif- 

 fers from the new variety in its smaller size, shorter canal, and the 

 presence of a well-marked sulcus on the anterior portion of the pillar. 



Genus Tritonopusus Beck 



TRITONOFUSUS FORTUNASENSIS, n. sp. 

 Plate 22, figures 4a and 46 



Shell small, elongate, regularly fusiform, with seven or eight 

 smooth convex whorls; spire high; apex acute; whorls evenly convex, 

 unsculptured except for axial lines of growth and a faint indication 

 of spiral threads, which are invisible without the aid of a lense ; 

 suture distinct, impressed; aperture elliptical, elongated, outer lip 

 thin ; inner lip incrusted ; canal short, nearly straight. 



Dimensions. — Altitude of type specimen, canal defective, 30 mm. ; 

 maximum diameter of shell, 13 mm. ; length of the aperture, 13.5 mm. ; 

 maximum width of the aperture, 5 mm. ; apical angle, 30 degrees. 



Occurrence. — The figured specimens of this species were obtained 

 from beds which are believed to be of the Miocene age, occurring at 

 the mouth of Bear River, Humboldt County, California. University 

 of California Locality 1863. 



