TURBINACEA. 109 
the axis of the shell; operculum horny, orbicular, with nu- 
merous whorls. Obs. Lamarck distinguishes this genus from 
Turbo, by the general form, which is more conical, and the 
aperture which is angulated, while that of Turbo is rounded. 
Monodonta or Odontis, is only separated on account of the notch 
at the termination of the columella. But these characters glide 
so imperceptibly from one genus to the other, that there is no 
line of demarcation to be found, but in the operculum. Ac- 
cordingly, Mr. Sowerby (in Gen. of Sh. 37) has stated his reasons 
for considering, as Trochi, all the species which have horny 
opercula; and as Turbines, all those which have testaceous 
opercula. Fig. 358 to 360. 
TROPAYUM. Sow. CrioceratirEs. 
TRO’PHON. Montf. Murex Magellanicus, Auct. and several 
other species which belong more properly to Fusus than to 
Murex. ~ 
TRUNCATED. (Truncus, cut short.) Terminating abruptly, as 
it were, cut short. Hz. Solen ensis, fig. 60. 
TRUNCATULINA. D’Orb. A genus of microscopic Forami- 
nifera, 
TUBA. Lea. A genus of small fossil shells, described as re- 
sembling Turzo, but with the aperture more like that of ME- 
LANA. T. striata, fig. 369. 
TUBERCLE. (Tuberculus.) A small swelling excrescence. 
TUBERCULATED. Having a number of small lumps or 
pimples, as Turrilites, fig. 483. 
TUBICINEL'LA. Lam. ( Tubicen, a trumpeter.) Order. Sessile 
Cirripedes, Lam. Descr. A cylindrical tube, composed of six 
elongated valves jointed together side by side, striated longitu- 
dinally, surrounded by concentric rings; aperture circular, en- 
closed by an operculum of four valves, placed perpendicularly 
in anepiphragm. Obs. The Tubicinellze are found with nearly 
the whole shell buried in the thick skin of the whale. T. Balze- 
narum, fig. 14. 
TU’BICOLA. Lam. (Tuba, a tube; cola, an inhabitant.) A 
family of the order Conchifera Dimyaria, Lam. containing the 
genera Aspergillum, Clavagella, Fistulana, Septaria, Teredina, 
Teredo, Gastrochzna and Xylophaga. Fig. 44 to 54. 
TU’BIVALVES. Bl. Shells composed of two valves connected 
with a tube. 
TURBINA’CEA. Bl. The sixth family of Polythalamacea, Bl. 
containing the genera Cibicides and Rotalites, microscopic Fo- 
raminifera. 
TURBINA’CEA. Lam. A family of the first section of the order 
Trachelipoda, Lam. containing the genera Solarium, Rotella, 
Trochus, Monodonta, Turbo, Planaxis, Phasianella, Turritella, 
_ and others enumerated in explanation of figures 353 to 371. 
