30 CALIFORNIA ACADEMY OF SCIENCES. 



toes are webbed. The skin on top of the head is not 

 divided into scales. There are two supracaudal plates. 

 The tail is moderate or long. 



I. — Clemmys marmorata (Baird & Girard). Pacific 

 Terrapin. 



Emys marmorata, B. k G., Proc. Ac. Nat. Sci. Phila., 1852, p. 177 



(type locality Puget Sound). 

 Emys nigra. Hallow., Proc. Ac. Nat. Sci. Phila., 1854, p. 91 (type 



locality Posa Creek, Lower [^Southern] California); Hal- 

 low., U. S. Pac. R. K. Siiiv., X, 1859, Pt. lY, p. .3, pi. I. 

 Actinemys marmorata Agassiz, Contr. Nat. Hist. U. S., I, 1857, p. 



444, II, pi. Ill, tigs. 5-8; Girard, U. S. Explor. Exped., Herp., 



1858, p. 465, pi. XXXII. 

 Clemmys marmorata Stjiauch, Mem. Ac. St. Petersb. (7), V, No. 7, 



1862, p. 108; Boulexger, Cat. Cheloniaus Brit. Mus., 1889, p. 



110; Stej-NEGER, N. A. Fauua, No. 7, 1893, p. 162. 

 Clemmys Wosnessenslyi, Strauch, Mem. Ac. St. Petersb. (7), V, 



No. 7, 1862, p. 114, pi. (type locality Sacramento River, 



California). 

 Geoclemys marmorata. Gray, Snppl. Cat. Shield Kept. Brit. Mus., 



1870, p. 27. 

 Che.lopus marmoratus, Cope. Boll. U. S. Nat. Mns., No. 1, 1875, p. 



53; Yarrow, Bull. U. S. Nat. Mns., No. 24, 1882, p. 36. 



Description. — Shell broad and low, broader posteriorly 

 than anteriorly, more nearly round in young than in 

 adults. Young with a median dorsal ridge not present 

 in adults. Vertebrals five, broader than long. Costals 

 four, first longest, second highest, last smallest. Nuchal 

 very narrow. Marginals twelve on each side, supracau- 

 dals being distinct. Plastron large, extending forward 

 about as far as carapace, weakly notched posteriorly, 

 truncate anteriorly. Its gular plates smallest, triangu- 

 lar. Pectorals not much smaller than abdominals. 

 Anals large, median suture between them longer than 

 that of any other plastral plates. Bridge formed of 

 pectoral and abdominal plates. Axillary and inguinal 

 plates very small or absent. Head large, more or less 



