Mr. W. Clark on the Animal of Dentalium Tarentinum. 321 
lated, reticulation regular with quadrangular areole, and covered 
with many slender linear tubular spines or their bases, somewhat 
quincuncially arranged ; spines smooth, dilated at the base, a 
little above which they remain of nearly uniform size throughout 
or very slightly tapering, and are regularly and transversely sul- 
cated or contracted, giving the spines a beaded or jointed ap- 
pearance. 
The general form of the shell and quincuncial arrangement of 
the spines resemble S. aculeata, Kutorga, but as that author does 
not figure or allude to any reticulated structure or the monili- 
form spines*, this is considered to be distinct ; unfortunately 
the specimen is much compressed, so that all the characters are 
not fully shown, and I have provisionally given the name of 
S. anglica until it can be compared with all the Russian species. 
Locality. From the Wenlock shale near Dudley. Collection 
of Mr. J. Gray. 
EXPLANATION OF PLATE VII. 
Fig. 1. Siphonotreta anglica. a. Shell, natural size. 6. Shell, magnified 
view. c. Spines enlarged. d. Portion of ditto, magnified. e. Outer 
surface of shell, magnified. 
Fig. 2.a. Siphonotreta verrucosa, 6. Side view. c. Surface of shell, mag- 
nified. d. Interior of dorsal valve. 
Fig. 3.a. Schizotreta= Orbiculoidea, D’Orb., O. Forbesiz. b. Showing lon- 
gitudinal furrow and contracted perforation. 
Fig. 4. Acrotreta = Cyrtia? a. Dorsal valve. 6. Ventral valve. 
Fig. 5. Aulonotreta = Obolus. 
XXXIII.—On the Animal of Dentalium Tarentinum. 
By Wiiii1am Cxrarg, Esq. 
To the Editors of the Annals of Natural History. 
GENTLEMEN, Norfolk Crescent, Bath, Sept. 1, 1849. 
Tue animal I am about to present to your notice exhibits a 
series of characters of the highest interest, in its anatomy and 
functional developments, some of which are so anomalous that 
it must be considered one of the most singular of the testaceous 
mollusca. 
From my observations in the September Number of the ‘An- 
nals,’ it appears that the minute species of the genus Caecum, 
from their configuration, have generally been located with the 
Dentalia, though it will be seen that there is little concordance 
* The moniliform character of the spines may not be peculiar to this 
species, but will probably be found to belong to the whole genus, when the 
spines of the other species are carefully examined by a higher magnifying 
power than that used by Dr. Kutorga. 
Ann. & Mag. N. Hist. Ser. 2. Vol. iv. 22 
