THEE CONCHOLOGISTS? < 
EXCHANGE SI 
FAMILY STREPOMATID. 
Genus Pleurocera, Rafinesque. 
77.— Pleurocera subulare, Lea. 
Mr. Lea’s description of this species is as 
follows : 
Shell elevated and acutely turrited, horn col- 
ored; apex acute; whorls about 12, flat, cari- 
nate on the middle of the body-whorl; base 
angulated; aperture white and one-fourth the 
length of the shell. 
This remarkably fine shell, as found here, is 
so variable that in some respects it would be 
extremely difficult to reconcile it with Mr. Lea’s 
descriptions and observations. It varies greatly 
in the number of its whorls, ranging from 10 
to I2 in number. Some specimens are of a 
very dark horn color, others very light; some 
have a very dark purple epidermis with purple 
columella. Some forms are striate, others 
smooth, and while many are very finely banded, 
others are devoid of bands. It also varies in 
the number of carinze on the body-whorl, which 
usually range from five to seyen In many, 
the whorls are very flat, while in others they 
are quite convex, and some specimens have 
from one to three revolving striz. Again,some 
individuals are rugosely striate on all the su- 
perior whorls. "The Family Strepomatidze is 
represented in North America by eight sub- 
genera, with several hundred so- Pealled species, 
but it is a singular fact that Mercer Co., Illinois, 
has but one species of this very numerous 
family. Our Pleurocera subulare is usually a 
very abundant shell here, being found in all 
our sloughs, lakes, creeks and rivers. The 
small lakes of the Bay Island are full of this 
species, and in July and August vast numbers 
of them may be found along the margin of the 
river, clinging to drift-wood, where they have 
- been carried by a sudden rise in the waters 
from the different lakes in the Bay. I have 
specimens of this shell from Northern Minne- 
sota, collected in or near the Mississippi River, 
and from different stations along the river as 
far south as St. Louis, Mo. 
FAMILY RISSOIDA. 
The Family Rissoidze seems to be represent- 
ed in this country by four sub-genera or genera, 
viz: Bythinella, Moquin-Tandon ; Somatogy- 
rus, Gill; Amnicola, Gould and Haldeman; 
and Pomatiopsis, Tryon, embracing eight spe- 
cies in all. 
Genus Bythinella, Moquin-Tandon. 
78.—Lythinella obtusa, Lea. 
This shell, as found here, is sub-cylindrical, 
rather thin, very light horn color, translucent, 
smooth, slightly perforate; spire short; sutures 
impressed; whorls four, always truncate, con- 
vex, aperture nearly round. 
It is by no means a common species. I find 
it sparingly at times of very low water in the 
channels of the river sloughs from June to 
September. In localities where found at all it 
is usually quite abundant. Of several hundred 
specimens taken in the channel of Upper Cowan 
Slough in 1880, every specimen was truncate, 
only the four whorls remaining. It is usually 
found associated with Azicola, Somatogyrus 
and Lioplax subcarinata. The cause of its 
truncated apex is unknown to me as the shells 
of other species taken with it have perfect 
spires. 
( Zo be continued.) 
NECROLOGY. 
Professor Ferdinand WVanderveer 
the distinguished geologist, died at his resi- 
dence, 1805 Arch St., Philadelphia, December 
21st, 1887, aged 58 years. He was a native of 
Westfield, Mass., and made his first explora- 
tion in 1853 for Professor James*Hall, of New 
York, in the “ Bad Lands” of Dakota, in which 
region, and in adjacent States and ‘Territories, 
he spent more than twenty years. ‘The de- 
ceased filled the chair of Geology and Miner- 
alogy in the University of Pennsylvania from 
1365 to 1872, and had charge of the U.S. 
Geological Survey of the Territories from 1867 
until 1873 
Hayden, 
George W. Puterbaugh, Conchologist, of 
Elkhart, Ind., diéd of heart disease, November 
29th, 1887, after nearly one year’s illness. 
Andrew Garrett, Conchologist, ee at Hua- 
hine, Society Islands, Noy ember 1887, aged 
65 years. 
