331 



A. Prefrontals fused; ventrals 141-154; scales 15-17; a white dot on each 



scale Trimetopon .gracile (Gtinther) . 



This is Ablabes gracilis Gtinther 

 1872, Ann. Mag. Nat. Hist. (4), 9, 

 p. 18, pi. 3, fig. D; Cartago, Costa 

 Rica; type, Brit. Mus. Nat. Hist, 

 no. 71-11-22-19, 20. It includes 

 Trimetopon pliolepis Cope 1885, 

 Proc. Amer. Phil. Soc. 22, p. 177; 

 San Jose, Costa Rica. The British 

 Museum has it from Turrialba and 

 from La Palma. I have taken it 

 from the latter locality. 

 AA. Prefrontals fused; ventrals 122; scales 15; uniform, back of head white. 



Trimetopon simile, sp. nov. 

 AAA. Two prefrontals; ventrals 141-153; scales 15; a lateral white stripe. 



Trimetopon barbouri, sp. nov. 



Trimetopon simile, sp. nov. 



Type. — Museum of Comparative Zoology no. 15263, received from the 

 Museo Nacional de Costa Rica. 



Type locality. — Reventazon, Costa Rica ( = La Junta) . 



Description. — Scales 15; ventrals 122; anal divided; caudals 69; prefrontals 

 fused; oculars 1-2; temporal 1-1; supralabiais 7, infralabials 7; third and 

 fourth supralabiais are below the eye; four infralabials are in contact with the 

 anterior chin shields which are longer than those posteriorly; black, white 

 below; head white as far forward as middle of frontal, and including third 

 labial; a black spot on seventh labial; length 155 mm., tail 50 mm. 



Trimetopon barbouri, sp. nov. 



Type. — Museum of Comparative Zoology no. 23877. 



Type locality. — Pedro Miguel, Canal Zone, Panama. 



Description. — Male: scales 15; ventrals 153; anal divided; caudals 58; 

 oculars 1-2; temporals 1-1; two prefrontals; two nasals; supralabiais 7, 

 infralabials 8; third and fourth supralabiais in contact with eye; four infrala- 

 bials in contact with anterior chin shields; darkish, light below; no light collar; 

 a stripe from eye to fifth and sixth labials; a stripe from parietal on second 

 temporal and seventh labial; a light stripe on fifth scale row and upper half 

 of fourth; first, second, and one-half of third rows lighter; length 260 mm., 

 tail 65 mm. 



Variation. — Of four from Ancon (Mus. Comp. Zool. no. 23873- 

 23876) two have ventrals 141 and 149. 



Remarks. — The genus is composed of these three obviously 

 related forms, but harbour/', with its normal prefrontals, is not 

 very remote from some of the Central American forms of Liophis 

 (Rhadinea) , approaching such forms as calligaster and seperaster. 



