EXPLORATION OF ALASKA. 201 
and the spermatocysta, the color of the gland yellowish-white, on the 
left side of the anterior part a central yellow mass; the duct of 
the mucous gland rather short. 
All the former genera of Doridide belonged to the large group of 
Doridide cryptobranchiate ;! the following are to be registered in the 
group of Doridide eleutherobranchiate (D. phanerobranchiate). 
This section is also characterized by the non-retractility of the gill, 
by a sucking-crop connected with the bulbus pharyngeus and by a 
peculiar armature of the tongue, consisting usually of a single large 
lateral plate and a single or several outer plates. This group seems 
chiefly limited to northern climes, and contains at present the genera 
Akiodoris, Acanthodoris, Adalaria, Lamellidoris, Goniodoris and 
Doridunculus,? also Ancula, Drepania’ and Idalia. 
AKIODORIS, Bergh. 
Akiodoris, Bgh. Gattungen nordischer Doridey, 1. c., 1879, p. 354. 
Forma ut in Lamellidoridibus. Notheum supra granulosum. 
Branchia non retractilis, e foliis tripinnatis non multis et ad modum 
ferri equini positis formata. Caput latum, veliforme; tentaculis 
brevibus, lobiformibus. Aperture rhinophoriales integra. 
Discus labialis sine armatura. Ingluvies buccalis bulbo connata. 
Radula rhachide quasi nuda ; pleuris dentibus lateralibus depressis non 
multis ; (12-13) quorum duo intimi fortiores, quasi subhamati. Penis 
glande uncis simplicibus, furcatis vel palmatis armatus. Vagina in- 
dumento valloso peculiari instructa. 
The animals belonging to this group resemble externally especially 
the Lamellidorides. The back is finely granulated; the head large, 
veil-shaped, with short tentacles, which are lobate and pointed. The 
openings of the rhinophor-holes with plain margins, surrounded by 
several larger papille. The non retractile branchia nearly horseshoe- 
shaped, consisting of a mediocre number of leaves. The lip-disk 
' Cf. my ‘*Gattungen nordischer Doriden,”’ 1. ¢. p. 341. 
2 The genus Doridunculus of G. O. Sars (Moll. regionis arctice Norveg., 
1878, p. 809. Tab. 27, fig. 2a-d, Tab. XIV, fig. 5), which externally ap- 
proaches Goniodoris and other Doridida eleutherobranchiate in the char- 
acter of the radula, is hitherto only known from the northeastern part of 
the Atlantic (Lofoten), and by a single species (D. echinulatus, S.). 
° In the Ancule and Drepanie the penis is armed as in so many Doridide 
with a series of small hooks. 
