59 
shell, and not jumble together under one name shells so diverse in these 
characters. 
By the kind permission of Miss Cooke, of the World Shell Store, 
here in San Diego, I have had the privilege of examining the large lot of 
this variety collected by the late Captain Geo. D. Porter, on Guadalupe 
Island, Lower California, that are now in her possession. 
Three hundred and twenty of these shells show the following varia- 
tion in the number of holes: 
One had 4 holes; 
Five had 6 holes; 
Twenty-four had 7 holes; 
Thirty-two had 8 holes; 
Thirty-one had g holes; 
Sixty-three had 10 holes; 
Seventy had 11 holes; 
Sixty-five had 12 holes; 
Twenty-six had 13 holes; 
Two had 14 holes; 
One had 15 holes. 
Miss Cooke reports finding 12 specimens in this same lot with 16 holes, 
but these were packed away and not accessible at this time. 
The shells average a little smaller and a little thinner than 
HI, cracherodti, white the form is more circular, generally. The color of 
the epidermis varies from a very dark blue, or black, to a yellowish blue 
and passes through various light and dark shades of brown. 
Unfortunately there were none among the lot examined smaller than 
about three inches long, and these, with adults or larger shells, were 
well worn in the region of the spire, with the early sculpture characters 
destroyed. 
There is evidence enough, however, on the half-grown and adults 
among this lot to warrant the assertion that the sculpturing is similar in 
the young state or on the young shells of this variety, to the typical or 
normal HY. cracherodi?. 
With this knowledge of the variations cf the holes and sculpturing of 
the shells of A/. cracherodiz7, we may now briefly consider its mutations in 
the opposite direction. 
FHTaliotis cracherodit, var. holzner? (Hemphill). 
I have before me three shells that, while they possess all the charac- 
teristics of Halzotis cracherodiz, they are without perforations, and there 
is no evidence on these shells that they ever had any holes. Thus they 
have lost the most important generic character that separates the genus 
Haliotis from that of the genus Gena, which has smaller but similar 
shelis in every respect except the perforations, which are absent. These 
