60 
21. 
Dr. Maton’s and Mr. RAcxETT's 
lacustris. T. testa rhombea planiuscula alabra, umbone acuto. 
92. 
amnica. 
Linn. Gmel. p. 3942. 
Muller Verm. p. 204. n. 388. 
Chemn. Conch. 6. t. 13. f. 135. 
| Schrót. Flussconch. p. 191. n. 12. lola 4125] 
Mi ontagu Test. Brit. p 89. Curium lacustre. 
Habitat in rivis. Incola vivipara. — 
Testa $s poll. longa, 4t, lata, glabra, tenuis, pellucida, cornei coloris, sub 
epidermide fusca. Valvule versus marginem complanate seu depressze. 
Umbones valde prominentes. Cardo dente primario simplici in altera 
valvula, in altera bifido, cum dentibus lateralibus in alterutra valvula. 
Distinguitur a T. cornea; quod subrhombea, umbones des d 
margo compressus. 
Discovered by Mr. Swaimon: ina siet near Bul- 
strode. Found by Mr. Montagu near Hatch, Devon; 
in the Avon at Lackham ; and àt Wedhampton, Wilts. 
TN testa. oblique subovata, t 
— Gualt. Test. t T- 4 ©, e. 
Chemn. Conch. 6. t. 13. ff. 194. Ed 
Muller Verm. p. 205. n. 389. 
Linn. Gmel. p. 3242. — 
Maton in Act. Soc. Linn. 3. Be 44. 4.13. f 37, Se X. 
rivalis. 
Donovan Brit. Shells, t.. 6A. f. 2. T. rivalis. 
| eny i in Hutch. Dorset. t. 7. f. 2. a. 
yu Test. Brit. p. 86. Cardium ETE 
n rivis, rarior. Incola vivipara. - E 
Tota 3 poll. longa,. + lata, coloris cornei, rdg: Ss latioribus, anterius 
~~ planiuscula, cardinis dentibus duriusculis prominulis. Differt a T. cor- 
mea, quod umbones acutiores, ct cardo versus extremitatem nec ad 
medium teste, (Maton.) 
First 
