236 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



1. mterstinctus, it is more abundant in the deeper water. One 

 specimen in alcohol [S. S. B, 236] is close to if not identical 

 with the var. puncfatus Whiteaves. 



Thiele ( :10, p. 87, 107) transfers this species to Callisto- 

 chiton, but this step I do not yet feel ready to follow. 



11. Ischnochiton (Lepidozona) mertensii (Middendorff) 



Numerous specimens of this species are in the collection 

 taken between tides and dredged (15-20 fathoms) at Forres- 

 ter Island, and between tides at the Waterfall Cannery, Prince 

 of Wales Island. At Forrester Island Mr. Willett found it 

 one of the two most abundant chitons in his dredge. The 

 specimens are almost all of the plain red-brown variety, the 

 girdle obscurely maculated in two shades of brown. Less 

 common, but equally constant in their peculiarities, are two 

 other color forms, analogous variations of which are also 

 commonly seen in California suites of this species: 1) a 

 form in which the valves are irregularly maculated with 

 various shades of brown, the alternate bands of color on the 

 girdle being usually quite regular and prominent; 2) a form 

 in which the jugal areas of the second and seventh valves are 

 usually darker than the general red-brown ground color, and 

 help to set off a cream-colored band nearly as wide as the 

 valves, which extends down the side slopes and across the 

 girdle, the latter being otherwise nearly unicolored. 



12. Ischnochiton (Lepidozona) w^illetti, new species 



Numerous specimens occurring at Forrester Island in 15 to 

 20 fathoms in company with /. mertensii, might easily be over- 

 looked as another color variety of the latter, but appear upon 

 careful examination to represent an undescribed species, which 

 may be briefly treated as follows : 



Diagnosis: Shell rather large, regularly elliptical (fig. 1); 

 elevated, with an angular dorsal ridge and arcuate side slopes. 

 General surface indistinctly granulose. 



Anterior valve with 35-45 low, occasionally bifurcating, 

 radiating ribs, separated by shallow distinct grooves and bear- 

 ing a variable number (normally 8 to 10) of small, well sep- 



