Dr Fleming on the British Testaceous Annelides. 239 
asserted, in the “ Philosophy of Zoology,” vol. ii. p. 97. that re- 
lics of the genera Dentalium and. Spirorbis had been found in 
the strata belonging to the Coal Formation ; and added, at the 
same time, that he had failed to procure authentic examples 
from any rock older than the hiferior Oolite 
In the following observations, an attempt is made to give a 
condensed view of the history, not only of the recent species, 
but of those which have become extinct, in order to exhibit the 
changes which this tribe has experienced during the different 
stages of the Earth's formation. Several circumstances prevent 
me from giving the subject all the illustration which may seem 
requisite. The few additional facts, hovfever, which are here 
recorded, will not fail to interest those who occupy themselves 
with the characters of our recent species, or who are anxious to 
determine the physical distribution of our extinct kinds. 
I. 
Testaceous Annelides, with the shell free. 
Genus DENTALIUM. — Apex perforated. The shell is round and 
tapering. The sides of the body of the animal are furnished 
with tufts of bristles, and at the posterior extremity there is a 
radiated disc. 
A. Recent Species. 
a. Shell furnished with longitudinal striae or ridges. 
Species 1. D.dentalis Shell marked with about twenty striae. Linn. Syst. 
1263. — D. striatum of Montagu, Test. Brit. 495. On the coast of Cornwall 
and Devon, Montagu. 
This shell is about half an inch in length. Diameter at the mouth of the 
shell, where there are a few faint rings, is about one line, and it retrally 
tapers to a fine point. 
2. octangulatum. — Shell with eight ribs, and three intermediate striae. Do- 
novan, Br. Sh. V. tab. 162. Lelant, Cornv/all, Miss Pocock. 
The number of intermediate striae may serve to distinguish it from the 
Dentaliam striatulum of Gmelin, with which British writers seem dis- 
posed to confound it. 
b. Shell destitute of longitudinal markings. 
3. D. entalis.—Qom.mm. Tooth Shell. — Shell tapering regularly from the 
one extremity to the other. Linn. Syst. 1263. — Borl. Corn. 276. tab. Ixxviii. 
fig. 5. — Penn. Brit. Zool. iv. p. 145. tab. xc. fig. 154. — Don. Brit. Sh, tab. 48. 
Common on all our shores, but usually in a dead state. 
The shell is frequently marked with circular wrinkles and bands. It is 
probably an inhabitant of deep water. The shell, inhabited by a Siphun- 
culus, the characters of which have not been determined, is frequently 
found entangled in the skate- lines in the estuary of the Forth. 
* Dentalites occur in the Shell Limestone which lies under the Inferior 
Oolite in the vicinity of Weimar; and in Limestone of the coal formation in 
Silesia. SerpuUtes in Mountain Limestone in Gothland, and in Shell Limc= 
stone in different parts of Germany.— Ed. 
