56 



DUNN — PACIFIC COAST AMBYSTOMIDAE 



rP.N.E.Z.C. 

 I Vol. VII 



Examination of specimens of Ranodon olympicus Gaige (Occ. 

 Papers Mus. Zool. Univ. Michigan, no. 40, p. 2, 1917), have 

 convinced me that it has very little to do with Ranodon sihiricus, 

 and would best stand alone. 



RHYACOTRITON gen. nov. 



Type : Ranodon olympicus Gaige. 



Diagnosis. — An Ambystomid salamander with a ring-shaped otoglossal 



cartilage, no second epibranchial, premaxillas with large nasal processes 



embracing a fontanelle,no na- 

 sals, frontal bordering nares, 

 separate prefrontals and lach- 

 rymals, vomerine teeth in two 

 short series; larva with no 

 dorsal fin-fold on body; ypsi- 

 loid cartilage aborted; lungs 

 greatly reduced (7 nmi. long 

 in a specimen measuring 125 

 mm.) toes 4 or 5, free. Colu- 

 mella with broad and plate- 

 like expansion, not fused with 

 walls of otic capsule, opercu- 

 lum very small. 



Note: Save for the names 

 of the ear bones, I have fol- 

 lowed the recommendations 



of the 'Conunittee on the Nomenclature of the Cranial Elements in the 



Permian Tetrapoda.' (Bull. Geol. Soc. Amer., 28, pp. 973-986, 1917.) 

 All figures are of an adult female of Rhyacotriton olympicus, M. C. Z., 



no. 5880. They are camera drawings enlarged about ten diameters. 



Figure 1. Dorsal view of fore part of skulL 

 (Maxilla and lachrymal removed on right 

 side.) 



M = Maxilla. PM = Premaxilla. V = 

 Prevomer. L = LachrymaL PF = Pre- 

 frontal F = Frontal. 



Distribution: OljmipicMts., Washington. 



Cope proposed to divide the salamanders of this group into 

 two famines — one, to include Ambystoma, Linguelapsus and 

 Chondrotus (= Dicamptodon Strauch), and the other, Ranodon, 

 Hynohius, SalamandreUa, Batrachuperus and Onychodactylus. 

 The characters were, for the Ambystomidae, presence of oto- 

 glossal and absence of second epibranchial, and, for the Hynobi- 



