110 THE NAUTILUS. 
occasional extra development, have been very generally ignored.” 
Even “ families” have been based on the presence or absence of the 
caudal pore; but it need hardly be said that such groups are 
violently unnatural. 
It is now proposed to unite all of the groups having the pedal 
grooves developed, into a superfamily to be called AULACOPoDaA, 
equivalent in value to the AGNATHA (so-called, including Sedeni- 
tide), or to the group composed of Helicide, Bulimulide, Cylindrel- 
lide, Pupide aud Achatinide, which may be called HoLopopa. 
The American Awlacopoda may be tabulated as follows: 
I. Marginal teeth with narrow, lengthened basal-plates, either uni- 
cuspid and thorn-like, or bicuspid by elevation of outer on 
middle cusp. 
a. Foot-margin wide; shell more or less spiral; ovotestis 
imbedded in liver, ZONITID.®. 
aa. Foot-margin narrow; shell a flat internal plate, not 
spiral ; ovotestis free from liver; slugs, LimMacip ®. 
II. Marginal teeth with short, wide and squarish basal-plates with 
one or several cusps, the outer cusp never elevated on middle 
cusp. 
a. Shell spiral, usually wholly external, ENpopontTip&% 
aa. Shell non-spiral, internal, more or less obsolete or want- 
ing; slugs. 
b. A vestigial shell present; mantle small, anterior, 
ARIONID®. 
bb. No shell; mantle covering the whole upper sur- 
face, PHILOMYCID®. 
Most of these families contain genera with, and genera without a 
caudal mucus pore. The Limacide and Arionide are degenerate 
so far as the shell is concerned, and have doubtless descended from 
the ancestral Zonitide and Endodontide respectively. 
North American Genera. 
ZONITIDH comprises Omphalina, Vitrinizonites, Vitrea, Gastrodonta, 
Pecilozonites, Guppya, Conulus, Pristiloma and Vitrina. See Nav- 
TILUS, June, 1895, p. 18. 
2 Exceptions need not be noted-here; but I cannot refrain from mentioning 
that the importance of the pedal grooves has been fully recognized by a_bril- 
liant Australian malacologist in dealing with the Charopa group. 
