158 Proceedings of the Biological Society of Washington. 



Sta. Cecilia — Banana farm in the Bananito River district, 

 south along the coast below Port Limon. Same general condi- 

 tions as Zent. 



This permitted a short visit to the following environmental 

 complexes: Tropical rain forest of the Atlantic coastal plain — 

 Zent, Monteverde, Guapiles, Sta. Cecelia; subtropical zone on 

 the mountains — Navarro; Temperate zone on the high volcanoes 

 — Irazii, Poas; tropical, no rain forest, Pacific Coastal Plain — 

 Orotino. 



Sibynomorphus ruthveni, sp. nov. 



Type M. C. Z. No. 15,549 from the Aguacate Mts., Costa Rica. 



Body strongly compressed anteriorly, less compressed along the mid 

 body region, strongly compressed again posteriorly; tail diminishing sud- 

 denly in diameter just posteriorly to the vent; eye large with vertical 

 pupil; rostral pentagonal, slightly wider than high, almost invisible from 

 above; internasals small, their suture about one third of that between the 

 prefrontals, which extend deeply over the canthal region and enter the 

 orbit extensively; frontal longer than wide, about equal to distance from tip 

 of snout, nearly one third shorter than the length of the suture between the 

 parietals; nasal partially divided with a nostril slightly longer than high; 

 loreal twice as long as high, entering eye; no preocular; two postoculars, 

 the lower slightly the larger; temporals 1+2; seven or eight upper labials, 

 fourth and fifth only entering orbit, sixth greatly enlarged; mental region 

 can not be described owing to injury; but evidently no median genial; first 

 lower labials in contact behind symphysial and a pair of large longitudinal 

 genials, scales in 15 rows without apical pits, median row not sensibly 

 enlarged or 13 rows with rows on each side of median row slightly enlarged, 

 ventrals 165; anal entire; subcaudals 79. 



Color in alcohol; banded dark brown and whitish; the brown bands 

 anteriorly thrice as wide as the light bands posteriorly equal and of solid 

 color while the whitish bands are clouded by groups of small streaks and 

 flecks of darker; the dark rings cross the body in a slanting direction so 

 that they tend to alternate on the belly. The head is dark anteriorly and 

 counting this there are twenty-five dark bands about the body and thirteen 

 about the tail. 



Total length, 425 mm.; tail, 110 mm. 



The following species of Sibynomorphus are known from Costa Rica: 

 S. bicolor (Giinther); *S. annulata (Gunther); S. articulata (Cope); S. argiLS 

 (Cope) and S. pidiventris (Cope). 



This form is about equally allied with annulata and articulata. 



Syrrhophus lutosus, sp. nov. 



Type M. C. Z. 8023, from Navarro, Costa Rica; E. R. Dunn collector 1920. 



Size small, body depressed; head as broad or slightly broader than the 



body; as broad as long; snout blunt with very ill defined canthus rostralis; 



