EXPLORATION OF ALASKA. 219 
The central nervous system was as above mentioned, and also the 
eyes (their nervi optici rather long), and the otocysts (the number of 
the otokonia about one hundred). The bulbus pharyngeus as usual ; 
on the tongue sixteen rows of teeth, farther backwards eighteen rows 
of developed and four of younger teeth; the total number of rows, 
thirty-eight. The plates as above; the length of the median plates 
0.05 to 0.058 mm.; the height of the anterior large lateral plates 
about 0.14 mm., of the posterior about 0.17 mm.; the number of den- 
ticles on these plates mostly fifteen to twenty. The vesica fellea was 
at the left side of the pylorus. 
8, L. hystricina, Bergh. 
LL. hystricina, Bergh, Mal. Untersuch., 1. ¢., 1878, p. 614, Tab. lxviii, 
fig. 17-23. 
Color ccerulescens. 
Dentes laterales margine interno denticulati sed non usque ad 
apicem. 
Habitat. Oceanum Pacificum (insula Kyska). 
One specimen of this species was found by Dall, at Kyska Island 
(Aleutians), on rocky bottom, at a depth of ten fathoms, in June, 
1873. According to Dall, the color of the living animal is bluish. 
The specimen preserved in spirits was 9.5 mm. in length, reached 
a breadth of 6.0 mm., and a height of the true body (without the 
papille) of 3.5 mm.; the breadth of the foremost part of the foot 
-was 5.3 mm., the height of the rhinophoria was about 2.1 mm., of the 
branchia about 1.2 mm., of the dorsal papille 1.2 mm. The color 
was uniformly whitish. 
The form was oval, the back not very convex. The head rather 
large, formed like a velum, that is radiately folded, and has its side 
parts connected with the ends of the anterior margin of the foot ;, in 
the middle of the hinder part of the under side of the velum is a trans- 
verse slit, in which the small mouth-pore opens. The opening of the 
rhinophor-holes was nearly round, with the margin rather thin, here 
were three papille of the same kind as on the back; the rhinophoria 
stout, the club with about twenty leaves. The back covered all over 
with mostly stout, club-shaped papillz, apparently set without order, 
and extending nearly out to the very margin of the mantle, which is 
thin and has on the upper side smaller, cylindrical or club-shaped 
papille. The papill all firmly adherent to the skin, the spicules shin- 
ing through all over on the back and in the papille. The branchial 
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