36 The Molluscan Family Planorhidae 



May 7 a capsule was laid which measured 7 by 4.5 mm. in area and contained twenty- 

 two eggs. Development was not obser\ed. 



Hclisoma traskii (Lea). Six shells of this species, preserved in alcohol, received 

 from Mr. Stanley Siegfus of Bakersfield, California, had eleven egg capsules on the 

 shells, containing 394 eggs. A capsule containing fifty eggs is figured (13) on plate 52. 

 The specimens were from the Buena Vista Canal, outlet of Kern Lake, California, near 

 the type locality for traskii. The capsules and eggs are noted below: 

 1 shell with 2 capsules containing 16 and 24 eggs. 

 1 shell with 2 capsules containing 45 and 42 eggs. 

 1 shell with 1 capsule containing 10 eggs. 

 1 shell with 2 capsules containing 35 and 85 eggs. 

 1 shell with 3 capsules containing 35. 22. and 20 eggs. 

 1 shell with 1 capsule containing 50 eggs. 



Mociuin-Tandon (1855, pp. 425-439) collected egg capsules from water bodies in 

 the environs of Toulouse, France, and obser\ed the development of some of the 

 embryos. Some of his observations are recorded below : 



Segrnentina nitida (Miiller). Nine egg capsules containing 3, 4, 5, 6, 7, and 8 eggs, 

 the capsules measuring 0.25 to 1.5 mm. in diameter. Development occupied ten to 

 twelve daj^s. 



Hippeutis jontanus (Lightfoot). Several capsules with 3, 4, 5, and rarely 6 eggs 

 in each capsule. 



Gyrorbis co7)iplanatus (Linn.) {^ Planorbis planorbis (Linn.)). Eight capsules 

 containing 10, 11, 13, 16, 17, and 21 eggs. 



Gyrorbis carinatus (Beck in Moller) { ^ Plnnorbis cnrinatus). Capsules contain- 

 ing ten to twenty eggs each. Development occupied ten to fifteen days. 



Gyrorbis vortex (Linn.) {^^ Anisus vortex (Linn.) ). Ten to twelve eggs in a cap- 

 sule which were 4 mm. in diameter. Development required ten to twelve days. 



Plnnorbis albus Miiller {^ Gyraulus albus (Miiller)). Capsules 3 to 4 mm. in 

 diameter containing four to ten eggs. 



Planorbis contortus Linn. {= Bathyomphahis contort us (Linn.) ). Capsules 3 mm. 

 in diameter containing six to eight eggs. Development occupied ten to twelve days. 



Planorbis corneus (Linn.) {^ Planorbarius corneus (Linn.)). Egg capsules 9, 

 11, 12, 13, and 15 mm. in diameter containing twelve to forty eggs each. Development 

 required fifteen to sixteen days. 



Brooks (1880) has recorded the early stages in the development of the small snail 

 Gyrauhis parvus (Say) {= Planorbis parvus Say). 



