82 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



Creek, and three were obtained at Horsetown, Shasta 

 County, California. L.ytoceras duvaliamun d'Orbigny is 

 found in the Neocomian of Europe. 



The types of this species are among the collections of 

 the University of California. 



20. Lytoceras (Tetragonites) jacksonense, sp. nov. 



Plate V, Figs. 124-125. 



Shell moderately compressed, rounded, smooth; size of type 6.33 cm. in 

 diameter; umbilicus rather narrow, walls steep, rounded on the shoulders; 

 involution covering the larger part of the preceding coil; section subcircular, 

 somewhat quadrate, slightly thicker near the umbilical shoulder, from whic^i 

 zone the sides slope gently toward the periphery. Faint grooves are to be 

 seen obliquely crossing the sides and inclining forward, and forming upon 

 the ventral surface a wide, backward curve, very much as is seen in the next 

 species, to which this one is somewhat related. Faint lines of growth are 

 barely perceptible upon the portions of test yet remaining, which are parallel 

 to the grooves. The suture consists of four or five very much divided sad- 

 dles, narrow, and unequally bifid, the outer branch of which is the smaller. 

 The lobes are relatively wider, with branches terminating in pointed denti- 

 cles. The division of the lobes is more equally bifid than that of the sad- 

 dles. Both lobes and saddles diminish uniformly in size from the e.xternal 

 side inward to the umbilicus. The small siphonal saddle is narrow and 

 denticulate. 



Occurrence. — A single specimen of this shell was ob- 

 tained from the Forty-nine Mine, near Phoenix, Oregon. 

 The locality has been referred to the Lower Chico beds in 

 the body of this paper. 



The type of the species is in the California Academy of 

 Sciences. 



21. Lytoceras (Gaudryceras) sacya Forbes. 



Ammonites sacya Forbes, Trans. Geol. Soc. Lond., Ser. II, Vol. VII, 



1845-56, p. 113. 

 Ammonites sacya (Forbes) Stol., Pal. Ind., Vol. I, p. 154, PI. LXXV. 

 Ammo7iites whitfieyi 0\v.^, Pal. Cal., Vol. II, p. 134, PI. XXII, 1869. 

 Lytoceras sacya Whiteaves, Mes. Foss., Vol. I, 1876-84, Pt. I, p. 43, etc. 

 Lytoceras (Gaudryceras) sacya Whiteaves, Mes. Foss., Vol. I, 1876-84, 



Pt. IV, p. 270. 



In the upper portion of the Horse*town beds this species 

 is fairly abundant and generally takes the place of 



