32 CALIFORNIA ACADEMY OF SCIENCES. 



California to British Columbia. It has been taken at 

 both San Diego and Puget Sound, as well as at many 

 intermediate localities, some of which are: Mojave 

 River,* Posa Creek, South fork of Kern River near 

 Kernville, Mt. Diablo, Monterey, Santa Cruz, Peniten- 

 tia Creek, Coyote Creek, Palo Alto, San Fraiicisquito 

 Creek, Los Gatos, San Francisco, San Rafael, Sonoma, 

 Nicasio, Sacramento River, McCloud River, Pitt River, 

 California; Klamath Falls, Oregon; Fort Steilacoom, 

 Washington. 



Habits. This is the terrapin of the San Francisco 

 markets, and is popularly known as the Mud Turtle or 

 Snapper. Very little is known of its habits. It is al- 

 most exclusively aquatic, preferring ponds and small 

 lakes to running water, but is sometimes encountered 

 on land while crossing from one body of water to an- 

 other. It is sometimes caught with hook and line, and 

 probably is omnivorous. A specimen which I kept 

 alive laid three eggs in June and another in August. 

 The eggs are elliptical, with hard,- white, limy shells, 

 and measure about, thirty-four by twenty-one millime- 

 tres. 



Genus 2. CHRYSEMYS. 



C'hrysemys, GRAY, Cat. Tort., Croc., Amphis., Brit. Mus., 1844, p, 

 27 (types picta and belli!) . 



The shell is rather narro\v, low or moderately high. 

 The plastron is immovably united to the carapace by a 

 broad bridge. There is a ridge on the alveolar surface 

 of the upper jaw parallel to the cutting edge. The in- 

 ternal openings of the nostrils are between the eyes. 

 The fingers and toes are fully webbed. The skin on top 

 of the head is not divided into scales. There are two 

 supracaudal plates. The tail is short or moderate. 



* Cooper, Proc. Cal. Ac. Sci., II, 1863, p. 121. 



