SHELLS OF LAKES AND STREAMS 



309 



Umbilicus Nearly Closed, 



Shell Horny, Northern 



IN Distribution 



Umbilicus Open, Shell Usu- 

 ally Porcellainous, 

 Southern in Distribution 



CQ 



D 



H 



m 



Q 



U1 



var. soiioiiiaciisis, Pilsl)ry, 

 PI. HI, Fig. 5, Sonoma 

 Lymnsea. 



L. c. huUmoides, Lea, PI. HI, 

 Fig. 1, Bulimus Lymnasa. 



var. sancti-joscphi, Hannibal, 

 PI. HI, Fig. 6, San Jose 

 Lvninsea. 



var. cockcrcUi, Pilsbry, PI. 

 HI, Fig. 2, Cockerell's 

 Lymnsea. 



L. ciihensis, Pfeififer, PI. HI, 

 Fig. 4, Cuban Lymnaea. 



var. bryanti. Baker, PI. HI, 

 Fig. 3, Walker's Lymnaea. 



{Flanorbidd^) 



In the hills east of Madrone, CaL, are two pretty 

 little lakes of great depth set end to end on top of 

 a high ridge. About them is a dense growth ot oaks 

 and other trees. It is an ideal place to go and spend 

 the day alone with nature, lounging in the shade, 

 listening to the birds and myriad insect life, and 

 watching the ever-changing colors of the torest. One 

 w^onders at the hurry and worry of lite. Oh, to live 

 like the lotus-eaters I Suddenh^ the fickle sun sets in 

 a blaze of glory behind the Santa Cruz Mountains. 

 Five miles to the depot and no supper till you get 

 home. 



In these Twin Lakes occur fine specimens of Plan- 

 orbis trivolvis^ Say, the Three-w^horled Planorbis, 

 Figures 292 and 293, a common species found all 

 over North America. The shell grows about itself 

 in a horizontal coil with a fiat 

 umbilicus and depressed spire. It 

 is over an inch across and marked 

 by fine growth ridges. Found in 

 quiet streams, ditches, and lakes. 

 There are a large number of so- Fig. 292. xf 



