CLASS GASTROPODA 
117 
V 
cate. Of this species, which is the largest of its race, I possess only four 
full-grown individuals; but they agree completely among themselves in 
their form. (Translation.) 
Sprachen nicht geographische Grunde dawider, so miisste ich diese 
Art fur identisch mit der Cal. pallida Brod. erklaren (Translation, Zool. 
Soc. of London, 1835, Vol. I, p. 204, PI. 29, fig. 3) Broderip’s Beschrei- 
bung beschrankt sich leider bloss auf Folgenden: Testa sordide alba, 
ovata, apice prominente: diam., % poll.; lat., 5 alt., %:—hab. ad insulas 
Falkland dictas.—Found under stones. (Middendorff.) 
Type in Academy, St. Petersburg. Type locality, St. Paul Island, 
Bering Sea. 
Range. Cape Franklin, Arctic Ocean, south and east to Sitka, Alaska; 
also Kamchatka. 
Crepidula onyx Sowerby, 1825 
Genera of Shells, No. 5:51. Conchologia Iconica, 8; species 9. 
Crep. testa oblongo-ovata, crassiuscula, intus extusque fusca, rufo- 
lineata, intus saturation, livida; appendice subampla, plana, alba, margine 
medio emarginato. 
Shell oblong-ovate, rather thick, brown within and without, rayed with 
red lines, interiorly darker, livid; appendage rather large, flat, white, edge 
notched in the middle. (Conchologia Iconica .) 
Type in Museum Cuming. Type locality, Panama. 
Range. Monterey, California, to Panama. 
Crepidula norrisiarum Williamson, 1905 
Nautilus, 19:51. 
There is another variety of Crepidula rugosa Nutt, found on Norrisia 
norrisii Sby.these shells are of a light magenta-pink in the 
interior. These slipper shells are usually much flatter than typical C. ru¬ 
gosa, and the form of the septum or deck also varies. Besides variation 
in color and form the Norrisia specimens are more porcellanous than Cre¬ 
pidula rugosa (but not so much so as the form found on Lunatia) and 
the texture does not run into layers as in the typical C. rugosa. Some years 
ago this form was often distributed by collectors and labeled Crepidula 
adunca Sby.While some of the forms found upon Norrisia have 
the remote apex of C. adunca, I have never seen one with the “short, 
deeply sunk and slanting deck, and a hole above it passing up the spire,” 
as described by Philip P. Carpenter in his catalogue of Mazatlan Mollusca 
[ 719 ] 
