328 MANUAL OF THE MOLLUSCA, 
sinuses in the skin, from which it returns to the auricle by two 
lateral veins, without having circulated through the gills. The 
heart is contained in a pericardium to which is attached a small 
ventricle, or portal heart, for impelling blood to the liver; the 
hepatic veins run side by side with the arteries and open into a 
circular vein, surrounding the vent, and supplying the gills. 
Only hepatic blood, therefore, circulates through the gills. In 
AZolis there are no special gills, but the gastro-hepatic papillz 
are accompanied by veins which transmit blood to the auricle. 
The skin acts as an aecessory breathing-organ; it performs the 
function entirely in the Hlysiade, and in the other families, when 
by accident the branchiee are destroyed. The water on the gills 
is renewed by ciliary action. The fry is provided with a trans- 
parent, nautiloid shell, closed by an operculum, and swims with 
a lobed head-veil fringed with cilia, like the young of most 
other gasteropods. (Hancock and Embleton, Phil. Trans. 1852. 
An. Nat. Hist. 1843.) 
FamiIty VI.—Dorip@.* Sea-lemons. 
Animal oblong; gills plume-like, placed in a circle on the 
middle of the back; tentacles two; eye-specks immersed, 
behind the tentacles, not always visible in the adult; lingual 
membrane usually with numerous lateral teeth, rachis often 
edentulous; stomach simple; liver compact; skin strengthened 
with spicula, more or less definitely arranged. 
Doris, L. 
Eiymology, doris, a sea-nymph. 
Example, D. Johnstoni, Pl. XIII., Fig. 1. 
Synonyms, Dendrodoris, Eb. Hemidoris, Strp. 
Animal oval, depressed; mantle large, simple, covering thehead 
and foot; dorsal tentacles 2, clavate or conical, lamellated, retrac- 
tile within cavities; gills surrounding the vent on the posterior 
part of the back, retractile into a cavity; head with an oral 
veil, sometimes produced into labial tentacles; mouth with a 
lower mandible, consisting of two horny plates, united near 
the front, and having 2 projecting points; lingual teeth nume- 
rous, central small, laterals similar, hooked and sometimes 
serrated, 24-68 rows; 87-141 in a row; nidwmental ribbon 
rather wide, forming a spiral coil of few vyolutions (p. 41, 
Fig. 29). 
* Contracted from Doridide ; as the Greeks used Deucalides for Deucaliontiades, 
Ehrenberg divided the genus Doris into sections by the number and form of the gilis, 
characters of only specific importance. 
