GEiOIvOGY OF LA SALIvE: COUNTY. 105 



bottoms and prefer still waters. They are tenacious 

 of life, living- much longer out of water than any 

 other species I have taken, and emitting- when removed 

 from their native element, a peculiar snapping- noise. 

 I have seen them attack bug-s as larg-e as themselves 

 with the g-reatest ferocity and quickly draw them be- 

 neath the water. The shells are sinistral. 



Physa o-yrina. Say. — Shell oblong-, of a polished, 

 shining- appearance: color lig-ht yellowish; whirls five, 

 suture marked; apex acute; aperture more than half 

 the leng-th of the shell; labrum slig-htly thickened on 

 inner marg-in and ting-ed with a reddish line; leng-th 16 

 mill; fine, abundant. 



Physa Hildrethiana, Lea — This species is placed 

 by Mr. W. G. Binney, in the synonomy of P. gyrina. 

 Say; but I think they are distinct. The following- 

 describes my specimens, which are larg-e and well 

 developed. I obtained them from a pond in Deer Park* 

 My description is fuller than that of Dr. Lea. 



Shell elliptical, of a chestnut color, firmer in 

 texture than P. g-yrina, whirls five, spire obtusely ele- 

 vated; aperture nearly two-thirds the length of the 

 shell, and compressed; labrum sharp, with its inner 

 marg-in red; and further within the aperture, a chest- 

 nut colored line showing- outside a whitish color; 

 leng-th, 19 mill. 



Dr. Lea calls this the most remarkable Ph3^sa 

 found in this country. The pond from which I ob- 

 tained my specimens has the bad habit of g-etting- drv 

 every season. The remarkable size of the shells as 

 well as their shape attracted my notice. The species 

 disappear with the water, but for several successive 

 years have reappeared with its return; or, the ova de- 

 posited have served to perpetuate the family. The 

 above two species are all that I can vouch for as living- 



