TESTACELLA. 105 
disparity between the genera. Subula is the generic name given 
by some authors to the wide-mouth species. Fig. 427, 428. 
TEREBRATULA. (Terebratus, bored,) Fam. Brachiopoda, 
Lam. Order. Palliobranchiata, Bl. Descr. Inequivalve, equi- 
lateral, oval or sub-trigonal, ventricose or compressed, attached 
by a tendon passing through an opening in the dorsal, or upper 
and larger valve, the umbo of which advances beyond that of 
the other valve; hinge destitute of a ligament, with two teeth 
in the dorsal valve, locked into corresponding cavities in the 
ventral, or lower valve, and with two curious processes originat- 
ing at the umbo of the lower valve, presenting, in some species, 
the appearance of fine winding tape, advancing towards the front 
of the valve. and again receding to the centre, where the ends 
unite; muscular impression, two, placed near the centre of each 
valve. Obs. The recent species of this genus are few. The 
fossil species are more numerous, occurring in the secondary 
and tertiary formations. T. Psittacea, Fig. 202. 
TEREDI'NA. (From Teredo.) Fam. Tubicole, Lam. Adesma- 
cea, Bl. Descr. Valves equal, inequilateral, with prominent um- 
bones, as it were soldered to the outside of the rounded end 
of a shelly tube, of which they form a part; aperture of the 
tube partly divided ; a flat accessary valve placed on the um- 
bones. Obs. This genus, which is only known in a fossil state, 
is distinguished from Teredo, by the valves being fixed on to the 
tube, and the tube being closed at one extremity. Fig. 46, 47, 
T. personata. 
TERE’DO. (A piercer.) Fam. Tubicole, Lam. Adesmacea, Bl. 
Descr. Valves equal, inequilateral; presenting when closed, an 
orbicular figure, with a large angular opening in front, and a 
rounded opening at the back; placed at the anterior extremity 
outside of an irregular, flexuous elongated tube, open at both 
ends; the anterior end divided into two apertures, opened and 
closed at the will of the animal, by two opercula. Obs. This 
is the genus of Mollusca, which is so remarkable for boring holes 
for their long tubes in wood, so as to give it a honey-comb ap- 
pearance. ‘I’. navalis, fig. 48; piece of bored wood, fig. 49. 
TESSELLATED. (Wrought in chequer-work.) A term applied 
to the colouring of shells, when arranged in regular defined 
patches, like a tessellated pavement. 
TESTACELLA. (Testa, a shell, dim.) Fam. Limacinea, Lam. 
and Bl. Deser. Haliotoid, compressed; aperture wide, oblique ; 
columella flat, oblique; spire short, flat, consisting of less than 
two whorls. Obs. This shell which is extremely small, com- 
pared to the animal, is placed on its back, near the posterior 
extremity. The animal is found in some of our gardens, and 
very much resembles a common slug. Fig. 261, T. Halio- 
toidea. 
Pp 
