RUNCINA. iL 
situated further forward, on right side of cephalic region. Stomach 
armed with four denticulate plates. 
Radula with the formula 1.1.1 (pl. 68, f. 36). Jaws present. 
A very distinct family of minute limacoid Tectibranchs, resem- 
bling Pleurobranchide somewhat in outward aspect, but differing 
widely in the dentition, the stomach-armature and the absence of 
rhinophores. Pelseneer believes Runcinide to belong to the Cephala- 
spidea (Chall. Rep. Zool. pt. Ixvi, p. 97); I think this likely. 
The original discoverer of the European species, Quatrefages, 
placed it in his supposed degenerate group “ Phlebenterata,” charac- 
terized by lack of a circulating system, anus, etc. Forbes, who re- 
discovered it on the English coast, placed the group next to Lima- 
pontia, an arrangement in which some other authors concurred. 
Gray, however, in 1857, decided its affinities to be with Pleuro- 
branchide, Umbrellide and Tylodinide, a position retained by 
Vayssiére. The important work on the group by the latter author, 
together with that of Bergh on the genus I/dica, supplies all that is 
yet known of the internal anatomy of Runcinide. 
Synopsis of Genera. 
Genus Runcina Forbes. 
Tentacles or rhinophores none. Teeth of the radula denticulate. 
Shell reduced to a minute vestige buried in the posterior part of the 
integument. 
Genus Inpica Bergh. 
Small labial tentacles developed. Teeth not denticulate. Shell 
a small non-spiral calcareous plate, external and posterior on the 
back. 

Genus RUNCINA Forbes, 1853. 
Runcina Forses, Hist. Brit. Moll., i, p. 611, type R. hancocki.— 
Pelta QUATREFAGES, Ann. Sci. Nat. (3), 1, p. 151 (1844), type P. 
coronata.—VAYSSIERE, Ann. Sci. Nat. (6), xv, p. 6 (1883). Not 
Pelta Beck, Index Moll., p. 100 (1837). 
Shell membranous, internal and minute. Body lengthened, lima- 
ciform ; no tentaclesat sides of mouth. Teeth of radula denticulate. 
Type R. coronata. 
