APPENDIX. 363 
LIMN AIDE. 
Lymnea stagnalis. (Linn.) Lake Osoyoos, replaced west of the Cascades 
by L. Sumassii. 
Lymnea Sumassti. (Baird: Nov. Sp.) 
Testa elongata, attenuata, cornea, fragili; anfractibus 
sex, ultimo ceteris duplo majore; apertura mediocri; 
columella forte plicata; superficie externa, sub lente, 
creberrime et minutissime decussata. 
This species of Limncea approaches L. elodes of Say, 
but is more elongated, more fragile, and has the colu- 
mella very strongly plicated. The surface of the shell, 
when seen under a lens of moderate power, is finely 
decussately striated. It is of a horny colour, and is of 
an elongated shape. Long., largest, 14 inch; lat. } inch. 
—Hab. Sumass Prairie, Fraser River, British Columbia. 
(Brit. Mus.) 
Lymnea megasoma. (Say.) Lake Osoyoos, and streams west of Rocky 
Mountains. 
Physa heterostropha. (Say.) Found only east of Cascades. 
Physa Lordi. (Baird: Nov. Sp.) 
Testa tenui, majuscula, cornea, tumida, gibbosa, 
apertura magna; labro acuto, linea alba seu fusca ex- 
terne notato; superficie externa minutissime decussata ; 
anfractibus sex, duobus primis minutis, nigro tinctis, 
ultimo tumido, ceteris quadruplo majore. 
This species is one of the largest of the genus, and is 
much swollen and gibbous. The outer lip is generally 
marked with a streak of brown edged with white, which 
