214 SCIENTIFIC RESULTS OF THE 
a little larger than the bulbus. The radula brownish-yellow, with 
nine rows of teeth, further back fifteen developed and two younger 
rows, the total number being twenty-six. The teeth quite as above, 
dark, horn-colored in their thicker parts; the median ones reaching a 
height of 0.16 mm. The salivary glands as above-mentioned. 
The biliary sac uncommonly small. The black contents of the 
rectum consisting of undeterminable animal matter, mixed with larger 
and smaller pieces of small crustacea. The liver much flattened on 
the right anterior half. 
The anterior genital mass large, about 7.0 mm. long, 5.0 mm. high, 
and 3.0 mm. thick. The ampulla of the hermaphroditic duct whitish, 
forming a long ansa, about 5.0 mm. long. The spermatoduct shorter 
than in the other form, otherwise, with the penis, as in that form. 
The spermatotheca yellowish, short, sac-shaped, of a largest diameter 
of 3.0 mm.; the spermatocysts about 0.3 mm. long, pyriform. The 
mucous gland chalk-white and brownish-gray. 
Of another variety, Dall, in August, 1872, obtained six specimens, 
in Sanborn Harbor (Shumagin Ids.), on stony bottom, at low water. 
According to Dall, the color of the back of the living animal is 
‘‘red-brown, with whitish papille.” The color of the backs of 
the specimens preserved in spirits was rather uniformly, dirty brown- 
yellowish, commonly much lighter on the middle, the papilla whitish ; 
the gill and the rhinophoria of the color of the back; the under side 
of the whole body yellowish; more whitish on the mantle. The 
length of the animals varied from 18.0 to 25.0 mm., by a breadth of 
11.0 to 16.0 mm., and a height of 8.0 to 120 mm.; the breadth of 
the foot 7.5 to 12.0 mm.; the height of the rhinophoria reaching 3.0 
mm., that of the gill 2.0 mm. The form as usual. The horseshoe 
shape of the gill very pronounced, the number of leaves, twenty-eight 
to thirty. The gill was surrounded by higher papille, which, in the 
largest specimen, reached the height of about 2.5 mm.; the space 
inclosed by the gill closely set with similar papillae, the largest (as 
large as the above mentioned) in the periphery. ‘The gill can be so 
deeply drawn back in its groove, that these external and internal 
papillae shut over and quite conceal it; the papille of the centre 
smaller; a crest or some few papilla in the median line go from the 
anus backwards, between the incurved ends of the gill. The anus 
small, very slightly prominent; the renal pore on the right side. The 
openings of the rhinophor-holes as usual, befure them the two usual 
papille, behind them a bare space. The papillx of the back quite as 
