— 40 — 



small. Canal straight, equaling the sub-oval mouth in length. Sinus 

 deep, situated at the angle. Length, 0.60 inch; breadth, 0.08; mouth 

 and canal, 0.34 long. 



Five specimens obtained, agreeing well in characters, at Marysville 

 Buttes, by Mr. Watts. This is quite near to Gabb's " Turris clayton- 

 ensisj'^ from near the Mt. Diablo coal mines, but a comparison with his 

 description shows marked difierences. Figures twice the natural size. 



The occurrence of seven new Pleurotomidse without many other 

 univalve shells, and especially the absence of the many forms of genera 

 allied to Fttsus described by Gabb, is a condition of distribution indi- 

 cating probably that a warmer sea existed where they are found, than 

 at most localities of similar age in California. 



Surcula inconstans n. sp. (PI. II, Figs. 20, 21.) 



Shell long, fusiform, whorls about ten, the first two turbinate, 

 smooth; third to sixth with ten or twelve transverse close-set ribs, 

 which, on the other four whorls, show only on the posterior half of 

 each, being replaced by eight or ten revolving riblets, forming a can- 

 cellated sculpture near middle, and toward the canal appearing alone. 

 Mouth narrow, sinus at angle, canal long. Length, 1.10; breadth, 0.25; 

 mouth, 0.50 inch. The figure is double the natural size. 



Pleurotoma perkinsiana n. sp. (PL II, Figs. 23, 24.) 



Very long and slender; whorls about ten, rounded, the first two 



turbinate, smooth; third with ten or twelve close-set vertical riblets, 



crossed by eight or ten revolving ones, the vertical gradually increasing 



to twenty-six on the body-whorl, forming a close beaded sculpture as 



far as the middle of body-whorl, while the revolving ribs continue 



alone on the body to canal. Varies also in relative strength of the two 



series of riblets, at different portions of spire. Sinus close to suture, 



canal straight, columella simple. Length, 0.60 inch; breadth, 0.15; 



mouth, about 0.25 long, 0.09 wide. This and the preceding have many 



characters alike, and are both variable in similar directions, so that at 



first they seemed varieties of one species, but the position of the sinus 



and differences in size and form distinguish them. Two specimens 



found at Marysville Buttes by Mr. Watts are figured; twice the natural 



size. 



Pleurotoma decipiens n. sp. (PI. II, Fig. 32.) 



Outline rhomboid; whorls seven (the first two imbedded in rock), 

 fifth to seventh sharply angled near middle, concavely sloping to the 

 suture behind the angle, flattened in front, body-whorl rounded in 

 front, forming nearly half of total length, and suddenly narrowing 

 into a canal as long as body-whorl; surface crossed by numerous 

 vertical raised lines, curved backward above the angle, straight below 



