50 THE NAUTILUS. 



The typical specimen of /. scabricostatus was orange with some 

 dark sutural dots, and the lateral areas are three ribbed, some low 

 pustules on the ribs. It was described from Cataliua Island. 



Both this species and the last are excessively rare in collections. 



II. 



A series of Chitons received from Miss Ida M. Shepard, of Long 

 Beach, Cal., contained specimens of a Callistochiton, which, while 

 allied to C. decoratus Cpr. of Lower California, yet differs in im- 

 portant respects. 

 Callistochiton decoratus var. punctocostatus n. v. 



Similar to C. decoratus in sculpture of end valves and lateral 

 areas ; but the central areas have no wide, smooth triangle at the 

 ridge, such as types of decoratus have (Man. of Conch., xiv, pi. 58, 

 fig. 18); being 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. 



III. 



Finally, with numerous other interesting species collected by Dr. 

 Benj. Sharp in Alaskan waters during the summer of 1895, there 

 were two specimens of a new and unusually distinct form, which we 

 dedicate to that accomplished zoologist. 



Traohydermon Sharpii n. sp. 



Shell oblong, elevated, carinated, the side slopes somewhat convex. 

 Surface to the naked eye smooth ; lustreless; slightly soiled white, 

 with some faint and ill-defined brownish spots on the lateral areas, 

 the girdle gray. 



Anterior valve smooth, with some indistinct concentric grooves; 

 the anterior slope shorter than the posterior edges; hind margin 

 emarginate. Intermediate valves wide and short, with slightly 

 arcuate margins at junction with girdle, hind margins emarginatu 

 Central areas very minutely roughened by diverging wrinkles; 

 lateral areas slightly raised, with a few arcuate faint grooves in the 

 direction of growth-lines. Posterior valve highest at its anterior 

 margin, the suboentral mucro but slightly projecting, the slope be- 

 hind it about straight. 



Interior white; valve callus strong; s-inus concave and shallow, 

 not defined at the edges ; sutural lamiiw but little projecting, broadly 

 rounded, invading the sinus. Insertion plates hardly longer than 



