482 



CALIFORNIA ACADEMY OF SCIENCES 



[Proc. 4th Ser 



Remarks: I am not sure what value should be put upon the 

 form here ranked as a subspecies of Carpenter's decoratus, but 

 if it be valid at all, I believe practically all the decoratus now- 

 found living in the waters of California proper must be referred 

 to it. Recent specimens show great variation in all details of 

 shape and sculpture, particularly in the very feature upon which 

 punctocostatus was principally founded in the first place, 

 namely, the extent to which the typical smooth area on the 

 jugum may be invaded by the sculpture of the pleural areas. 

 The typical decoratus from Lower California is said to have 

 a conspicuous, wide, rather sharply defined, triangular, smooth 

 area on the jugum of valves ii to viii. This feature is wanting 

 in typical punctocostatus, which is "somewhat irregularly pitted 

 toward the beaks, and with rows of pits on each side of a 

 small oblong smooth tract at the ridge ; most valves pitted 

 also on the ridge anteriorly" 19 . Even punctocostatus as thus 

 described does not represent the extreme found in the form I 

 here describe as C. d. fcrminicus, where the sculpturing is de- 

 veloped clear across the valves. As a matter of fact one finds 

 all transitions in the direction of typical decoratus. I have yet 

 to see two specimens with sculpture exactly similar in this 

 respect. 



The Deadman Island specimens, curiously enough, include no 

 median valves, but the tail valves show only a very narrow, 

 rib-like, smooth area on the jugum, or the sculpture may ex- 

 tend clear across, though becoming more or less obsolete as 

 the center is reached. The number of radial ribs in this series 

 of valves is uniformly 9, of longitudinal riblets 10 to 15 on a 

 side, and of slits, 9 to 11. The specimen illustrated (PI. XIV. 

 fig. 4) has the following caliper measurements : Length 3.7, 

 diameter 6.5, height 2.3 mm. 



"Pilsbry, H. A.— Nautilus, v. 10, p. 50, 1896. 



