EXPLORATION OF ALASKA. 239 
little sac, which seems to be homologous with the biliary sac (pancreas, 
autt.) of other Dorididx. Alder and Hancock, therefore, have de- 
nominated that part of the digestive tract as “stomach,” although it 
in no essential respect differs from the rest of the intestine, and is 
just like that part in the Chromodorides, and should be undoubtedly 
regarded as the pyloric part of thesintestine, when that sac opened 
lower down, as in the Chromodorides,' in the cavity, which is included 
in the liver, and seems to be the true stomach. The spermatoduct and 
the chief duct of the spermatotheca (vagina) are of very considerable 
length; the former consisting of two different parts, a superior softer, 
and an inferior very muscular part, internaliy clothed with an arma- 
ture, which is continuous through the penis. ‘This last is rather short, 
the superior part solid and projecting as an armed glans into the in- 
ferior, hollow part (preputium). The armature consists of rows of 
hooks continued in the interior of the organ, and, as mentioned above, 
farther upwards; quite like that of the Polyceride, Phyllidiidx’ 
and Doriopsidex.* 
About the biological relations of these forms very little is yet known 
and that only with reference to the typical species, through Alder and 
Hancock, as well as Meyer and Moebius. The spawn is figured by 
Alder and Hancock ‘1. ¢., Pl. 15, fig 9), and by Meyer and Moebius 
(1. ¢., fig. 13, 14); about the development nothing is yet known. 
The few known species of this genus seem limited to the northern 
parts of the Atlantic and of the Pacific. 
1. Acanthodoris pilosa (O. F. Miller). Oceanum Atlanticum et Pacificum. 
Doris pilosa, Cuv. : 
Doris stellata (Gm.), Cuy.°® 
1 Cf. my Malacolog. Unters. (Semper, Philipp., I, ii), Heft xi, 1877, p. 
464-494 ; Neue Nacktschnecken der Siidsee, ii, Journ. der Mus. Godeftroy, 
Heft viii, 1875, p. 72-82; ¢dem, iv, 1. c., Heft xiv, 1879, p. 1-21. 
2 Of. my Malacolog. Unters. (Semper, Philipp., II, ii), Heft xi, 1877 
(Trevelyana, Nembrotha). 
3 Of. my Bidr. til en Monogr. af Phyllidierne, Naturh., Tidskr. 3, R. V., 
1869; Malacolog. Unters. (Semper, Philipp., II, ii), Heft x, 1876, p. 377- 
387. 
4 Cf., 1. c., Heft x, 1876, p. 384-387; Journ. der Mus. Godeffroy, Heft 
viii, 1875, p. 82-94. 
5 According to Fischer (Note sur quelques especes du G. Doris, décrites 
par Cuvier, Journ de Conchyl. 3 sér. x, 1870, p. 290), the Doris stel’atu, 
Cuv., and the D. levis, Cuv , are identical with his D. pilosa, and this with 
the typical form of Miller. 
The D. stellata of Philippi seems a quite different form, a Platyd ris 
