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



42. Desmoceras sugatum Forbes. 



Plate III, Figs. 98-99. 



Ammonites sugata Forbes, Trans. Geol. Soc. Lond., 2nd Ser., Vol. VII, 

 1S45-56, p. 113, PI. X. Stoliczka, Paleont. Ind., Vol. I, p. 60, 

 PI. XXXII. 



Desmoceras sugata Yokoyama, Paleontographica 34, p. 185, PI. XX. 



Among the interesting species comprising a small collec- 

 tion of fossils from Shasta Valley is an undoubted repre- 

 sentative of Amviomtes sugata, as described and figured by 

 Stoliczka. The author had not access to the original de- 

 scription of Forbes, and can only judge of its identity with 

 the Indian species, trusting to the accuracy of Stoliczka's 

 determination. The well preserved specimens from Siski- 

 you County show clearly all the characteristics of the 

 Indian type, and leave no room to doubt the essential 

 identity. 



The shell is discoidal, very involute, smooth, flattened upon the sides, 

 keeled, and with narrow and deep uml)ilicus ; the keel is less noticeable 

 upon the younger portion of the coil ; one or two faint flexuous grooves are 

 seen near the aperture, bending considerably forward upon the ventral side. 

 The suture line consists of many lobes and saddles, six of each being visible 

 upon one side of the whorl and showing well their peculiarities ; saddles 

 bifid, with ultimate divisions rounded ; lobes trifid, with numerous pointed 

 denticles. The greatest diameter of the type specimen, which is probably 

 not an old one, is 2.7 cm. On a portion of the outer whorl, in which the test 

 is preserved, are faint lines of growth which curve strongly forward in cross- 

 ing the keel, indicating that the aperture had upon its ventral margin a long 

 projection or rostrum. These lines show also upon the cast of the shell, but 

 more faintly. 



Ocair7'encc. — According to Stoliczka, Ammonites stigata 

 occurs in both the Arrialoor and Trichinopoly groups of 

 Southern India; Yokoyama reports it from a similar hori- 

 zon of Japan; and in California it occurs in the Lower 

 Chico beds of Siski3^ou County, from which the present 

 specimens were obtained. At Henley, four specimens of 

 this species were obtained along with Placenticeras calif or- 

 nicum, P. facificiim, and very many others of the Lower 

 Chico. 



The type is in the collections of the California Academy 

 of Sciences. 



