EXPLORATION OF ALASKA. 235 
The color of the animals preserved in spirits was uniformly yel- 
lowish. The length was 13-15.0 mm., by a breadth of 8.5-9.5 and a 
height of 4-5.0 mm.; the breadth of the foot 6 mm.; the height of 
the rhinophoria about 2.5 mm., of the branchial leaves 1.0-1.3 mm. ; 
according to M. Sars the height of the rhinophoria is four to five times 
that of the tubercles of the back, (1. c. p. 16, also in one of his figures 
fig. 7). The form as usual; the back covered all over with large 
rounded tubercles, which rose to the height of 1.5 mm., and were of 
a similar breadth; they were sessile or more or less subpedunculate, 
sometimes set in indistinct longitudinal rows; between the larger 
tubercles everywhere were smaller ones of different sizes; on the 
margin of the back were tubercles of middle size or smaller; the 
spicula rather indistinct between and in the tubercles. The rhinophor- 
openings as usual, two large tubercles before them; the club of the 
organs with about twenty-five leaves. The gill with eight to twelve 
leaves ; according to M. Sars, the number of branchial leaves is ten— 
to Lovén, eight toten. A large (high) tubercle between the hindermost 
leaves, before it the low. anal papilla, and to the right side the renal 
pore; some few smaller papillze were spread over the space between 
the anus and the branchial leaves. The head large, broad; the short 
tentaculz pointed. The genital opening as usual. 
Six individuals were dissected. The peritoneum was colorless. 
The central nervous system rather flattened, especially the visceral 
ganglia, which lay on the outer side of and behind the cerebral ones, 
which were a little larger; the pedal ones larger than either of the 
other ganglia, situated perpendicularly upon the former. The proxi- 
mal olfactory ganglia bulbiform, a little smaller than the buccal ones ; 
no distal could be found. The length of the commissures equal to the 
‘largest diameter of the pedal ganglia; the subcerebro-pedal about 
three times as thick as the visceral. ‘The buccal ganglia of oval form, 
connected through a short commissure ; the gastro-cesophageal about 
one-sixth of the former in size, with one very large cell. 
The eyes with black pigment, yellow lens; the nervus opticus about 
as long as the largest diameter of the cerebral ganglion. he otocysts 
of the same size as the eyes, situated externally at the junction of 
the cerebral and the visceral ganglia; with about fifty ordinary 
otokonia, but among them four to six larger ones, of a diameter of 
about 0.025 mm. The leaves of the rhinophoria nearly without 
spicula; in the axes, and especially in the stalks, on the contrary, an 
enormous quantity of large spicula, in great part transversely situ- 
4 
