LATERAL LINE. BRAIN. 273 



fhali there is a well developed dermal skeleton, and in 

 some Anura bony plates, which are sometimes united to the 

 subjacent vertebrae, are present beneath the dorsal integument 

 {Ceratophrys, etc.). 



Horny thickenings of the epidermis are sometimes found on 

 the ends of the digits giving rise to claws (e.g. Onychodactylus , 

 Xenopus), and in other places (e.g. on cutaneous excrescences, 

 hand of male frog, etc.). In all Amphibians the stratum corneum 

 periodically peels off and the animal is said to cast its skin. 



Lateral line sense-organs are present in the larvae and in 

 aquatic forms on the head and in longitudinal rows (usually 

 three) on the body (Fig. 151). The latter are innervated by the 

 lateral line branch of the vagus. The skin is almost always 

 pigmented and the colours are often brilliant. The pigment is 



Fig. ]51. — Larva of Salamandra ma<:uiata (after Malbranc from Glaus). Ms, Us rows of 



lateral line sense-pits. 



found in the epidermis (brown or yellow), and in branched cells 

 in the cutis, where it may be black, brown, yellow or red. Colour 

 change * is a widespread phenomenon in Amphibians and is 

 under the control, though not necessarily the voluntary control, 

 of the nervous system. The secretion t of the cutaneous glands 

 is very generally poisonous, especially in those with bright 

 yellow markings, e.g. Salamandra maculosa, Bomhinator, 

 Dendrobates. 



The lateral muscles are divided into myomeres after the 

 piscine manner in the lower Urodeles, but in the higher forms 

 this segmentation is lost. 



The brain % is small and distinguished by the small size of 

 the cerebellum. The cerebral hemispheres are separate and 



* Biedermann, W., Pfliiger's Arch. Physiologie, 51, p. 455. 



f Boulenger, in Natural Science, 1, 1892. Paratoids are aggregations 

 of cutaneous glands forming swellings on the sides of the head of some 

 forms. 



X Burckhardt, R., " Hirn. u. Geruchsorgan von Triton u. Ichthyophis," 

 Z. f. w. Z., 152, 1891, p. 369. 



Z — II T 



