TEES CONCHOLOGISTS’ 
the mouth. The teeth which nearly close the 
aperture are situated far within and need a 
hand microscope to distinguish them, but by 
breaking off a portion of the lip they may be 
examined with ease. They are found abun- 
dantly in stagnant ponds, ditches, &c., where- 
ever there is decaying vegetable matter. I 
have often picked from a dozen to twenty on a 
single oak leaf and sometimes thirty to forty 
from a stone as large as my fist. Inhabits 
New England, Middle and Western States. 
SUB-FAMILY ANCYLIN:. 
This sub-family contains three genera, An- 
cylus, Latia and Gundlachia. Latia inhabits 
New Zealand. Gundlachia has five species, 
two of which inhabit the United States; one is 
found in California, and one in the District of 
Columbia. Ancylus has about fifty spe- 
cies, twenty of which inhabit the United States, 
and two make their homes in Rhode Island. 
139. Ancylus fuscus, Adams. 
Shell small, thin and pellucid when the epi- 
dermis is removed, oval, the entire outline 
regularly curved; apex elevated a little and 
turned to the right and rear of the centre. It 
is distinguished from all other species of An- 
cylus by its epidermis, which is brown, rough 
and course, projecting beyond the margin of 
the shell and extended in a plane with the 
object to which it may be attached, and thus 
appears to turn upward like the brim of an old 
slouch hat. Its length is 3-10, breadth 1-8, 
height 1-20 ofan inch. Within it is polished 
and shining. 
It was discovered by Mr. Kinne Prescott in 
a small rivulet in Andover, adhering to stones, 
and was described by Prof. Adams in the 
‘Boston, Journ. Natural History,” III, 320, 
1840, in the same year in Silliman’s Journal, 
XXXVIII, p. 396. Prof. Adams afterward 
found it at Mansfield, Mass. Dr. A. A.Gould, 
also found it at Fresh Pond, Cambridge, and 
it is quite common in R. J., in ponds and 
rivers, adhering to stones and to the empty 
valves of fresh-water clams. 
- EXCHANGE 3 
140. Ancylus paralellus, Hald. 
Synonym; Ancylus rivularis,Gould,non. Say. 
In October, 1817, Say published a descrip- 
tion of Ancylus rivularis. Owing to the mea- 
greness of the description, and perhaps having 
never seen Say’s type, Dr. Gould in the Inver- 
tebrata of Mass., 1841, applied Say’s name to 
our New England species. In the Second 
Edition, edited by Mr. Wm. G. Binney, this 
error is rectified, and the proper name of par- 
alellus, substituted. The Ancylus rivularis of 
Say is not found in New England. Ancylus 
paralellus is not very common in R. I. A few 
may be obtained in the Blackstone and in the 
Ten Mile River on stones near the shore in 
several places. It is a small, narrow, elongated- 
oval shell, thin and delicate, of a greenish tint; 
apex nearly central, leaning a little to the nght 
and rear; sides nearly parallel, both ends 
rounded; length, 1-4; breadth, 1-10 inch. 
Suborder Thalassophila contains three fami- 
lies, Amphibolidze (spiral and operculate) Sip- 
honariidee and Gadiniidze, (conical and not op- 
erculate) no representatives of which are found 
in the U. S. 
CLASS 4, SCAPHOPODA. 
Shell a hollow cylinder open at both ends. 
A simple straight or curved tube without spire. 
Animal carnivorous, burrowing in sand or mud 
in salt water. This Class contains one family, 
Dentalide, several genera and about one hun 
dred species. They are called tooth shells and 
the type is the Dentalium elephantinum, Linn. 
The only species inhabiting the eastern coast 
of the U S. are the D. dentale and D. striola- 
tum, both New England species but only found 
north of Cape Cod. 
With this chapter I close the description of 
all the univalve shells of R. I. Four of the 
five Classes of Mollusca have been treated of 
in these pages and the remaining one, Pelecy- 
poda, will be the subject of the succeeding 
chapters on the “Shell Bearing Mollusca of 
Rhode Island.” 
To be continued. 
