— 54 — 



flat. Anterior end strongly twisted in a wide canal (the aperture filled 

 with a hard matrix). Two revolving ridges between tubercles, and six 

 principal ones anterior to them ; also two or three fainter ones between 

 each pair, making thirty in all, crossed by the faint lines of growth. 

 Spire, 0.40 inch high; mouth, 1.50 inch long, 0.75 wide; canal 0.40 

 wide (broken off short). In surface characters it resembles Fulgur, with 

 the thick shell and canal of some Trophons. The great variations 

 found in different species of Fulgur, however, show us that this might 

 as well belong to Agasoma. It also resembles some of Gabb's Creta- 

 ceous genus Eripachya in outlines, but is decidedly Tertiary. It is 

 apparently the fossil figured in Prof. Blake's Report, pi. VIII, figs. 64, 

 65, and a, which Conrad did not venture to name, casts only being 

 figured. Figs. 72 and 72a, which he named '' Syctopus ocoyanus,'' may 

 represent a cast of a young shell, but it is too uncertain a name to be 

 retained. (This is given as Ficus ocoyanus in Gabb's list of unidenti- 

 fied fossils, and Ficula ocoyana in my Catalogue of Fossils, 1888.) Only 

 one fair specimen found, by Mr. Watts. 



FRESH-WATER FOSSILS. 



Limnea contracosta n. sp. (PI. V, Fig. 59.) 



Form broadly ovate, whorls five, rapidly enlarging from an obtuse 

 apex, and with convex outlines, to the very large body-whorl, which 

 forms three fourths of the total length, no umbilical fissure visible. 

 Length, 1.20 inch; breadth, 0.75; spire, 0.30. 



Specimens found with the two next species in a bed of laminated lig- 

 nite, discovered about 1868, along the westerly branch of San Pablo 

 Creek, on the stage road just south of Rocky Mound. A thin stratum 

 of lignite underlies several square miles around that locality, but its 

 exact age is still unsettled. On the east are deposits of marine Miocene 

 fossils, on the west altered Cretaceous rocks with ^^Aucella piochii.'^ The 

 lignite may therefore be a deposit formed in a Pliocene lake. None of 

 the other Tertiary fresh-water deposits yet examined in California con- 

 tain fossils like this. The coal-strata have evidently been uplifted to 

 an angle unusual in Pliocene deposits, but there is nothing to fix the 

 date of the volcanic outburst which is seen in Rocky Mound, three and 

 a half miles distant. 



Planorbis pabloanus n. sp. (PI. V, Fig, 57.) 



Form regularly cylindro-spiral, whorls three and a half, slowly 

 increasing, without sculpture, size moderate. Greater diameter, 0.60 

 inch; lesser, 0.48. The absence of distinctive characters in most of the 

 species of this genus, together with the flattening caused by pressure in 



