146 



VERTEBRATE ANIMALS OF THE UNITED STATES 



The lower Caudala are aquatic animals throughout life, the higher ones 

 are mostly terrestrial as adults, but must still live in moist places. 



The 1 50 species of Caudala are grouped in 3 suborders and are found 

 mostly in the temperate parts of the northern hemisphere; about 99 

 species occur in North America and 69 species in the United States. 



On the Identification of Caudate Amphibia. — The descriptions of 

 salmanders in this book apply to adult animals. The most important 

 descriptive features are the shape and appearance of the body and its 

 color, the length of the body in millimeters, including the tail, the length 



Fig. 64 Fig. 65 



Fig. 64. — The naso-labial groove of Desmognalhus fiisca: f, crescentic fold which closes 



the nostril when the head is submerged; gr, naso-labial groove which drains the nostril 



when the head emerges from the water; grl, labial groove; nl, orifices of glands {from 



"Whipple). 



Fig. 65. — The ypsiloid cartilage of Trilnrus viridescens: I, pubis; y, ypsiloid cartilage; 



the other letters refer to muscles (from Whipple). 



of the tail, the number of costal grooves between the fore and hind 

 limbs, the number of digits, and the position of the teeth, especially 

 those of the vomers and parasphenoid. The naso-labial groove, 

 a glandular groove passing from the nostril to the lip (Fig. 64), and the 

 plantar tubercles, which are elevations on the palms and soles, are also 

 often important. Several features of the internal structure are impor- 

 tant in a full analysis of the various groups, although a knowledge of 

 them is not usually necessary for the identification of species : these are 

 the shape of the vertebrae, the form and condition of the cranial bones 

 and cartilages, the presence or absence of the lungs and of the cartilage 

 which may lie in the ventral body wall just anterior to the pubis and is 

 called the ypsiloid cartilage (Fig. 65). 



