302 THE DOLABELLINAE. 
Visceral commissure usually very much shortened, except in Tethys and Dola- 
bella. Genital duct monaulic, the hermaphroditic duct connected with the 
penis by a ciliated groove. 
APLYSIIDAE. 
Animal lengthened, not protected by a shell, the neck and head narrower 
than the body; mouth a vertical fissure; anterior angles of the head produced 
into two tentacular lobes folded above; behind them the cylindrical or coni 
rhinophores, slit above, in front of which are the minute eyes. Parapodia 
recurved over the back, forming two lateral or dorsal lobes enclosing the mantle ~ 
and ctenidium. Genital orifice between the dorsal lobes, communicating by 
a long furrow with the evertible penis, which is near the anterior right tenta | 
Shell nearly or entirely covered by the mantle, uncoiled, in the form of a con 
cave plate, or absent. Mouth with corneous jaws and a large multiserial rad 
composed of similar teeth; stomach armed with horny nodules; anus behin d 
the branchial plume. — ) 
APLYSIINAE. 
Parapodial lobes well developed, their anterior ends separated; genital 
orifice in front of the ctenidium; radula with wide denticulate rhachidian 
teeth, and narrower serrate and denticulate laterals. Shell flexible. 
DOLABRIFERINAE. 
Parapodia considerably united behind, in front contiguous, separated only 
by the spermatic furrow; genital orifice in front of the ctenidium; shell cales 
reous or absent; radula with well-developed rhachidian teeth, larger than 
laterals. 
DOLABELLINAE. 
Parapodia scarcely mobile, united behind, inclosing a large branchial 
chamber, their anterior ends contiguous, separated by the spermatic furrow; 
the dorsal slit short. Posterior part of body obliquely truncate, bounded by — 
ridge; Genital orifice usually under the posterior part of the ctenidium; rad | 
with the rhachidian tooth rudimentary or nearly so, laterals very nume 
with long simple cusps; shell well developed, calcareous. 
