TRANSVERSE. 275 



scribed: "Fusiform, smooth ; the spire of very few whorls, and 

 not longer than the channel ; inner lip with a thick callosity at 

 the top ; the slit short and wide ; lineata, En. Meth. 440, f. 2, 

 clavicularis, lb. f. 4. filosa. En. Meth. 440, f. 6. lineolata. lb. 

 f. 11." Sw. p. 314. 



TOMOGERUS. Montf. Anastoma, Auct. Fig. 4/1. 



TONICHIA. Gray. Syn. B. M. p. 126. A genus composed of 

 those species of Chiton which have the margin smooth. 



TORNATELLA. Auct. Fam. Plicacea, Lam.— Dcscr. Oval, spi- 

 rally grooved ; spire short, rather obtuse, consisting of few 

 whorls ; aperture long, narrow, rounded anteriorly ; outer lip 

 simple ; inner lip thin, slightly spread, columella spiral, incras- 

 sated, confluent with the outer lip. The recent species are few. 

 Several fossil species occur in London Clay, Inferior Oolite and 

 Calcaire-grossier. Monoptygma, Lea, resembles this genus, but 

 has a fold on the inner lip. Fig. 343, T. solidula. 



TORTUOUS. {Tortnosus) Twisted. This adjective is sometimes 

 applied as a specific name ; as Area tortuosa. 



TRACHELIPODA. Lam. (rpa^jXoe, trachelos, a neck ; ico^a, 

 poda, foot.) The third order of the class Mollusca, in the system 

 of Lamarck. The trachelipodous mollusca are described as having 

 the posterior part of the body spirally twisted and separated from 

 the foot ; always enveloped in a shell. The foot is free, flat, 

 attached to the base of the neck. Shell spiral, and enclosing the 

 animal when at rest. This order contains the families, Coli- 

 macea, Lymnacea, Melaniana, Peristomiana, Neritacea, Janthinea, 

 Macrostomata, Scalariana, Plicacea, Canalifera, Alata, Purpuri- 

 fera, Columellaria, Convolutse. The genera belonging to these 

 families, are represented in the plates, fig. 264, to 462. 



TRANSVERSE. (Crosswise.) A shell is said to be transverse, 

 when its width is greater than its length, that is, when it is 

 longer from one side to the other than from the umbones to the 

 ventral margins. The term is applied by some authors to express 

 the direction of the lines of growth in bivalve shells, and the 

 spiral lines in spiral shells. See Concentric, 

 t 2 



