120 BULLETIN 34, UNITED STATES NATIONAL MUSEUM. 



somely colored. All are distinguished for their power of x^rojectingthe 

 tongue. Some of the species of Spelerpes, where this organ is free all 

 round, can project it entirely from the mouth, while the Geotriton fuscus 

 has almost the power of the chameleon in tliis respect, projecting the 

 tongue for a distance equal to one-half the entire length of the ani- 

 mal.* 



Appropriately to this habit, the basibranchial bone and its pair of 

 short hypohyal processes are free from the ceratohyals, thus admitting 

 of free movement, and the epibranchials are very long. In all of the 

 genera the extremity of the ceratohyal is attached to the quadrate, as 

 in the Amblystomid?e, showing that it is not this element which is pro- 

 jected. But in Geotriton and Spelerpes sp. the epibranchial is greatly 

 elongate, extending to the side of the nape and interscapular region, a 

 structure necessary to projectility. 



In the characters of the scapular and pelvic arches this family does 

 not differ from the Amblystomidte and Salamandridse. The foramen 

 which separates the procoracoid from the coracoid is well marked and 

 intermarginal ; in the Amblystomidte it is smaller, and in the Sala- 

 maudridfe marginal. .The femur always presents a strong trochanter. 

 It is weak in Stereochila marginatum. In Triturus and Diemyctylus it is 

 quite weak, but in Salamandra strong. 



In most of the genera of this family the enamel does not cover the 

 entire crown of the tooth. In Spelerpes ruber, longicaudus, and hellii, and 

 PletJiodon glutinosus and cinereus the external part of the crown termi- 

 nates in a transverse cutting edge, while the inner extremity is more 

 prolonged, leaving a transverse depression between the two. In Sp. 

 bellii the inner apex is transverse and ijrolonged a little beyond the ex- 

 ternal, while in the other Spelerpes and the Flethodon glutinosus the 

 inner crown is more prolonged and is incurved conic. In P. cinereus 

 it is a little more obtuse. In Desmognathus and the Amblystomidse 

 the two apices are of equal height and are both transverse cutting edges, 

 the outer narrowed in the former. In the larvse of Plethodontidse that 

 I have examined the crowns are simple. The teeth of Autodax are 

 more like those of Coecilia, or of Hylonomus of the Coal Measures, and 

 distinguish the gpmus from other Plethodontidse.t They are large, 

 compressed, and simple. 



This family is more remote in its skeletal characters from the Sala- 

 mandrida) and Pleurodelidiie than is the Amblystomidse. Thus the 

 absence of paraspheuoid brushes, the ossification of the tarsus and 

 carpus, and the persistence of the pterygoid bones are characters com- 

 mon to the two latter and wanting in the present family. On the other 

 hand, the non-prolongation posteriorly of the vomers, the articulation 

 of the ceratohyal with the quadrate, and the amphicoelous vertebra3 

 belong to this family and the Amblystomidse only. The position of the 



* Eiidinger in Sitzungsber. Akad. Wiss., Mtmicb, 1885, p. 109. 

 tSee Proceed. Acad. Nat. Sci., Phila., 18r)9, 124. 



