88 PROCEEDINGS OF THE ACADEMY OF [1880. 



The spermatoduct as usual, also the penis.* The spermatotheca and 

 the spermatocysta as usual. The mucous gland very small, whitish 

 and yellow. 



ACANTHODOEIS, Graj. 



Acanthodoris, Gray, Figs, of Moll. Animals, iv, 1850, p. 103, Guide Moll. 



Brit. Mas. 1857, p. 207. 

 AeaniJiodoris, Alder and Hancock, Mon. Brit. Nud. Moll., vii, 1855, p. 43, 



app. p. xvii. G. O. Sars, Moll. reg. arct. Norvegise, 1878, p. 308, 



Tab. xiv, fig. 4. 

 Acanthodoris, R. Bergh, Gattung. Nord. Doriden, 1. c, 1879, p. 35G-360. 



Forma corporis subdepressa. Nothaeum supra sat grosse villosum. 

 Branchia (non retractilis) e foliis tripinnatis non multis et in orbem 

 positis formata. 



Caput latum, veliforme ; tentaculis brevibus, lobiformibus. Margo 

 apertur«um rhinophorialium lobatus. 



Discus labialis armatura e hamulis minutis formata et infra cuticula 

 incrassata prominenti instructus. Lingua rhachide nuda ; pleuris an- 

 gustis dente laterali, hamiformi permagno et dentibus externie minutis- 

 (4-8). 



Ingluvies buccalis bulbo pharyngeo connata. 



Penis armatura e hamulis minutis formata instruetus. Vagina 

 lonsissima. 



'o- 



The genus Acanthodoris was established by Gray, to receive the 

 Doris pilosa with its non-retractile gill. Alder and Hancock adopted 

 the genus, made an anatomical examination of the typical form and 

 gave it natural characters, which were then adopted by Gray. In 

 several new malacological publications of a systematic nature the genus 

 has been omitted, and in the last twenty years no new information has 

 been published, until G. O. Sars lately gave some notes on the bulbus 

 pharyngeus. 



The Acanthodorides approach the Lamellidorides, yet differ ex- 

 ternally in the scattered soft villosities of the back and in the smaller 

 number of the leaves of the gill, which are arranged in a circle. 



Internally they differ still more, in the presence of a strong, oral 

 armature, in a different dentition (4 + 84-1+0 + 1+8-1-4), by a pecu- 



' Sars (1. c. p. 16) mentions and figures (fig. 8) the penis as "a large, 

 white, conical " organ. 



