Geol.— Vol. II.] ANDERSON— CRETACEOUS DEPOSITS. 99 



43. Desmoceras jugalis Gabh. 



Ammcmites jugalis Gabb (in part), Pal. Cal., Vol. II, p. 133, PI. XXII, figs. 

 12, 12a and lib; not figs. 13 and 13a, same plate. 



Perhaps no other CaHfornia species has caused so much 

 perplexity as Ammonites jugalis Gabb. In the Paleon- 

 tology of California, three species are figured and referred 

 to Ammonites jugalis. In the collections of the University 

 of California were found eight small specimens in one tray 

 labeled ^^ Am. jugalis Gabb," each with a label indicating 

 its locality. One, the type of fig. 5, Plate X, Vol. I, is a 

 typical Phylloceras ramosum Meek from the north side of 

 Mount Diablo. Another, labeled "Pioche's Coal Mine," 

 perhaps near Mount Diablo, is clearly a crushed specimen 

 of sea-urchin, and has been recognized by Dr. J. C. 

 Merriam as an example of a species recently discovered 

 in the Martinez Group, and to which he has given the 

 name Schizaster lecontei. This is apparently the speci- 

 men from which Gabb' claimed to have drawn figs. 5 and 

 6h^ which doubtless represent two distinct species of 

 Ammonites. Of the other specimens, five are perhaps 

 from Curry's, on the south side of Mount Diablo, and 

 belong to a distinct genus, Schluteria, mentioned in 

 another part of this paper, and the remaining one is a 

 small crushed specimen of perhaps the same genus from 

 Martinez. The species figured in the Paleontology of Cal- 

 ifornia (Vol. II, PL XXII, figs. 12, 12(7, lib), should be 

 selected as representing the type of Ammonites jugalis, and 

 this is apparently the conclusion arrived at by Stanton 

 (1895-96, p. 1031), who has studied the species carefully. 

 There can be little doubt that figs. 13 and 13^^ are from 

 a species not yet recognized, which is distinct from Am- 

 monites jugalis. This is plainly seen in the sections and 

 surface markings, as shown in the figures. 



1 Pal. Cal., Vol. II, p. 134. 



2 Pal. Cal., Vol. I, PI. X. 



^ Pal. Cal., Vol. II, PI. XXII. 



