APPENDIX. 363 



LIMNJEID.E. 



Lymnea stagnalis. (Linn.) Lake Osoyoos, replaced west of the Cascades 



by L. Sumassii. 



Lymnea Sumassii. (Baird: Nov. Sp.) 



Testa elongata, attenuata, cornea, fragili ; anfractibus 

 sex, ultimo cseteris 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, 1^ inch ; lat. ^ inch. 

 Hob. Sumass Prairie, Eraser Eiver, British Columbia. 

 (Brit.Mus.) 



Lymnea megasoma. (Say.) Lake Osoyoos, and streams west of Rocky 



Mountains. 

 Physa heterostropha. (Say.) Found only east of Cascades. 



Physa LordL (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, casteris 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 



