52 PROCEEDINGS OF THE ACADEMY OF [1880. 



4 



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 Dorididce belonored to the larfje "roup of 

 Dorididee cryptohranchiatse ;^ the following are to be registered in the 

 group of Dorididce eleiitherohranchiatse (D. phanerohrancliiatse). 

 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 nortliern climes, and contains at present the genera 

 Akiodoris, Acantlwdoris, Adalarid, LameUidoris, Goniodoris and 

 Doridunculus,'^ also Ancula, Drepania^ and Idalia. 



AKIODORIS, Bcrgh 

 Akiodoris, Bgh. Gattungen nordisclier Dorideu, 1. c, 1879, -p. 354. 



Forma ut in LameUidoridibiis. Nothseum supra granulosum. 

 Branchia non retractilis, e fuliis tripinnatis non multis et ad modum 

 ferri equini positis formata. Caput latum, veliforme ; tentaculis 

 brevibus, lobiformibus. Apei turte rhinophoriales integrse. 



Discus labialis sine armatura. Ingluvies buccalis bulbo connata. 

 Radula rhachide quasi nuda ; pleuris dentibus lateralibus depj'essis 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 LameUidorides. 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 papilla?. The non retractile branchia nearly horseshoe- 

 shaped, consisting of a mediocre number of leaves. The lip-disk 



^ Cf. my "Gattungen nordisclier Doriden," 1. c. p. 341. 



^ The genu?, Doridu7iculus of G. O. Sars fMoll. regionis ai'cticse Xorveg., 

 1878, p. 309. Tab. 27, fig. 2a~d, Tab. XIV, fig. 5), whicli externally ap- 

 proaches Goniodoris and other Dorididce eleutherobranchiaton in the char- 

 acter of the radula, is hitherto only known from the northeas'ern part of 

 the Atlantic (Lofoten), and by a single species {D. ecliinulatus, S. ). 



^ In the Ancula and Drepanice the penis is armed as in so many Dorididce 

 with a series of small hooks. 



