KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 48. N:o 1. 9 
Prosobranehia. 
Heart with the auricle before the ventricle; respiratory organ a ctenidium in front 
of the heart (seldom secondary branchie or none); nervous system of the streploneurous 
type; animal nearly always gonochoristic. 
Subordo I Diotocardia (Aspidobranchia). 
Heart with one (Docoglossa) or two (Rhipidoglossa) auricles; ctenidium bipin- 
nate; pedal ganglia not developed, replaced by longitudinal ganglious cords with 
transverse commissures. Shell never siphonated. 
Synopsis of Families. 
A. Docoglossa. 
Radula with 1—3 lateral teeth; heart on the left side of the body, before the 
rectum, with 1 auricle; no epipodium. Shell limpet shaped without internal callus 
and without slits; apex straight conic or inclined forward, never backward. 
1. A real ctenidium in the mantle cavity on the left side of the body; no accessory 
branchig. Radula without rhachian tooth, of the formula 1.2.(1.0.1).2.1 or 
(0) Fra SEEN Fam. Acmeide. 
2. No ectenidium in the mantle cavity; accessory branchige in the mantle furrow all 
around the foot. Radula usually without rhachian tooth; normal formula 3.1. 
(CEORURR Fam. Patellide. 
3. No ctenidium nor accessory branchige. Radula with a rhachian tooth, of the 
förmula 2:.0:1:0.2 Fam. Lepetide. 
B. Rbhipidoglossa. 
Radula usually with many laterals; heart in the median line of the body, 
pierced by the rectum, with 2 auricles; epipodium mostly present. Shell usually 
spirally twisted or, if limpet shaped, with posterior apex. 
KE. Sv. Vet. Akad. Handl. Band 48. N:o 1. 
N 
