I20 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



below this line upon the sides of the whorl, but all extending to ventral mar- 

 gin, where they terminate in equally prominent tubercules. This outer row 

 of tubercules shows a tendency to doubling, which can be detected upon all 

 shells above a diameter of 1.5 cm., though shown most clearly upon coils 

 above a diameter of 4 cm. and below 7 cm. The ribs bend more obliquely 

 forward at the inner node of this double row, which is considerably less con- 

 spicuous than the outer one. 



The ventral and dorsal margins have an abrupt truncation at maturity, and 

 above a diameter of 2 cm., but lose this character and become rounded in 

 old age, as they are in the very young stages. 



The keel and ribs seem to appear together just below the diarneter of 

 3 mm., the ribs appearing first in the ventral region. The keel,. which is at 

 first simple, begins to show crenulations at a diameter of 1.5 cm.,, which 

 gradually increase in prominence until maturity. In the older portions of the 

 shell these again decline. ■ ;,• 



The umbilicus of this shell is wide and shallow, occupying about one-third 

 of the entire diameter of the coil. Within the umbiHcus the thin, sharp ribs 

 and dorsal tubercules of the younger whorls are noticeable. 



The sutures consist of a ventral and one lateral lobe, supplemented by two 

 auxiliary lobes near and within the umbilicus. The saddles show a tendency 

 to become bifid, though this division has actually been seen on only the first 

 lateral saddle. Tlie lateral lobe is simple and elongated, with relatively small 

 subdivisions, amounting merely to short teeth. 



The name, S. knighteni, is proposed in recognition of 

 the kindly interest taken in this study by Mr. E, Knighten 

 Anderson, from whose property the larger part of this inter- 

 esting collection was obtained, and to whom the author is 

 indebted for first calling his attention to this important 

 locality. 



The type is in the collections of the California Academy 

 of Sciences. 



67. Schlcenbachia multicosta, sp. nov. 



Plate II, Figs. 41-47. 



Shell discoidal and compressed, umbilicus wide and shallow; moderately 

 involute, the outer whorl embracing about one-third, or less, of the inner 

 one; sides of whorl flattened, giving a narrow quadrangular outline to the 

 shell when viewed from behind; the sides ornamented with about fifty 

 oblique, flexuous ribs, which tend to bifurcate from tubercules occurring along 

 the inner margin of the whorl. The ribs curve forward in approaching the 

 outer margin of the whorl, and like the preceding species this one has a 

 double row of inconspicuous tubercules upon the ventral shoulders. The 

 ribs are generally rounded; the keel, which is simple and entire, lacks the 



