TEIOMPHALIA. 297 



and irridescent within, denticulated on the inner margin, rounded 

 anteriorly, truncated posteriorly ; hinge with four oblong, com- 

 pressed, diverging teeth in one valve, receiving between their 

 grooved sides, two similar teeth in the other ; ligament external, 

 thick ; muscular impressions two in each valve. — Obs. Only one 

 recent species of this marine genus is known, the T. pectinata, 

 which comes from New Holland ; and was formerly so rare, that 

 a much worn odd valve has been sold for a considerable sum. It 

 is of a brilliant pearly texture within, tinged with purple or 

 golden brown. Fossil species occur in Lias, upper and lower 

 Oolite, and Green-sand. T. Pectinata. PI. vii. fig. 139. 



TEIGONOSEMUS. Konig. A genus composed of species of 

 Terebratula, Auct. which have one valve produced into a beak, 

 perforated, or as it were truncated at the apex, differing from 

 Terebratula lyra. Lam. T. lyra. PI. xi. fig. 208. 



TEIGONOSTOMA. A sub-genus of Helix, with a trigonal aper- 

 ture. Gray's Turton, p. 139. 



TEIGONOTEETA. Konig. A genus composed of species of 

 Terebratula, Auct, which have the hinge of the larger valve pro- 

 duced into a triangular disc, divided by a triangular foramen in 

 the centre. Spirifer, Sowerby, belongs to this genus. Pig. 

 214, 215. 



TEILASMIS. Hind, Voy. Sulphur, p. 71, PL xxi. fig. 5. A small 

 pedunculated Cirripeda, described as having two principal valves 

 and a carina. From the characters of the animal and shell, how- 

 ever, Mr. Darwin has felt obliged to add several species to this 

 group, and these species having the terga developed, and the 

 scuture divided, could not properly be called trilasmis. In Mr. 

 Darwin's work they are described under the name Psecilasma. 



TEILOBATE. (Jpeig, three ; Xo/3oe, division, lobe.) Divided into 

 three lobes or principal parts. Ex. Malleus, Fig. 165, 



TEILOCTJLINA, D'Orbigny. A genus of microscopic Fora- 

 minifera. 



TEIPAETITE. {Tripartitus) composed of or divided into three 

 separate parts. 



TEIOMPHALIA. Sowerby, jun. (Tpia, three ; 6n<pd\ioi', um- 



