51 
Conclusions. 
From the above examination follows that the genus Runcinella 
is well separated from Runcina, above all in the following particulars: 
Anal and genital apertures are situated in the real posterior end 
of body; giils 4—5 with a doridoid arrangement round the anus; 
opaline giand consisting of isolated glandulae enclosed in an infra- 
anal sac; male opening close at the mouth; penis with a tubular 
giand but lacking terminal vesicula seminalis; vagina with a simple 
tubular bursa copulatrix. 
Runcinella represents a more advanced and specialized type, 
though in a few characters (e. g. penis) more primitive, than Runcina, 
with which it shares its chief organization. Its systematical position 
thus is to be established within the same family. This, beside 
Runcina, contains the genus Ildica of Bergh with a single species. 
The genus Runcina comprises the following 5 species: R. coronata 
Quatrefages 1844, capreensis Mazarelli 1893, calaritana Co- 
losi 1915, prasina Mbrch 1863 and inconspicua Verri 11 1903. 
Co los i (1915) arrives at the conclusion that the fam. Runci- 
nidæ should be removed from the Cephalaspidea (Bullidea) and 
made the type of a coordinate group Runcinidea. His opinion is, 
however, in some cases, e. g. concerning the genital system, based 
on interpretations of facts which seem to be debateable. In the 
present species at least the structure of the genital apparatus en- 
tirely corresponds to the Cephalaspidean type (type I in Lang, 1900), 
and there is no other character (except the giils) in which it dif- 
fers properly and positively — the absence of a shell being, of 
course, insufficient to motive a separation, as a reduction of the 
Shell is more or less complete in many Bullomorph genera. 
Fam. Pleurobranchidae. 
Bouvievia {Pieurobvanchus) aurantiaca Risso. 
Stewart Island: 34, 1 sp., 1. 18 (animal). — Auckland Island: 
41 (Masked Island), 1 sp., 1. 9 (animal). 
Bouvievia (Pleuvobvanchus) ovnala Cheeseman. 
North Island: 17, 2 sps., 1. 30 (animal). — 19, 1 sp., 1. 7 (animal). 
— See Addenda p. 86. 
4* 
