THE NAUTILUS. 



VOL. XXII. DECEMBER, 19O7. No. 8. 



ON A CYMATIUM NEW TO THE CALIFORNIAN FAUNA. 



BY WM. H. BALL. 



Having heard from Dr. R. H. Tremper that he had recently 

 obtained from the fishermen of San Pedro, a species of Cymatium 

 which could not be referred to any of the forms heretofore known 

 from that region, he was requested to send the specimens for exam- 

 ination. 



A careful study of it shows that it is different from any member of 

 the group previously known from either coast of America, but so 

 close to the Mediterranean " Triton " corrugatus Lamarck, that 

 it seems impossible to separate it more than varietally. 



Cymatium corrugatum var. Tremperi nov. Shell agreeing closely 

 with C. corrugatum except in the following particulars : the perios- 

 tracum in the latter is light colored, velvety, with the processes or 

 hairs of a uniformly even length ; in Tremperi it is blackish-brown, 

 coarse, lamellose with, on the varices, strong, sparse, projecting hairs 

 reaching 6 mm. in length. In all the specimens I have examined of 

 the Mediterranean shell, there are, between the revolving primary 

 ribs, numerous small subequal minor threads; while in Tremperi 

 there are in the channels only one or two coarse, irregular, markedly 

 larger riblets. The other differences are all apparently of an 

 individual character. The shell measures : length 85 ; aperture, 

 including the canal, 36 ; max. diam. 38 mm. There are five rather 

 prominent axial ribs on the last whorl between the last pair of vari- 

 ces. The operculum is exactly like that of the Mediterranean form. 



