18 THE NAUTILUS. 
to the writer by Dr. Wm. H. Dall, have furnished preparations of 
the teeth enabling us to fix the the generic positions of these inter- 
esting little species. P. pugetensis proves to be a Zonitid, with the 
dentition much like that of Pseudohyalina minuscula and milium, 
perfect laterals 4, as in minuscula, while miliwn has 2 or 38. The 
jaw, imperfect in my preparation, looks like that of minuscula. 
P. randolphii has the characteristic dentition of Punctum, and 
with pygmeum (v. minutissimum) and conspectum it makes three 
species of this genus for America. There are two in Europe, pyg- 
meum Drap. and massoti Bgt., and one in Africa, eryophilum Mar- 
tens. Some other minute Patuloids will doubtless prove to belong 
to Punctum when their dentition is examined. LP. randolphii has a 
narrower umbilicus than our other species. 
So ambiguous are the shell characters of these genera of small 
Zonitide and Endodontide that, as the event has proved, Dall was 
fully justified in the liberal use of question-marks in his provisional 
generic references. The moment their soft parts come under the 
microscope, broad distinctions between the groups appear, leaving 
no uncertainty as to the limits of the genera and families. The 
difficulty is to get the animals of these liliputian races alive or suit- 
ably preserved for dissection. 
The classification of the numerous groups and genera of Zonitide 
is still in an embryo condition. The forms with well-developed 
spiral shell inhabiting North America fall into groups as follows: 
a. 2 System bearing a long dart-sack surmounted by one or more 
coronal glands, and usually containing a slender, curved 
dart. Subfamily ARIOPHANTIN & Pils. 
b. Caudal mucus pore present; shell without opaque color- 
markings, Genus GASTRODONTA. 
ce. Shell with internal teeth or a layer of callus on the floor 
of last whorl, s.-g. Gastrodonta. 
cc. No internal teeth or callus. 
d. Surface polished, s.-g. Zonitoides. 
dd. Surface conspicuously striate or costulate, 
s.-g. Pseudohyalina. 
bb. No caudal pore; shell with streak, band or flame markings, 
Genus Pa:crLozoNIreEs. 
aw. Q System lacking dart-sack, ete. 
Subfamily ZONITINZ Pils- 
tile: 
