150 THE ANATOMY OF VERTEBRATED ANIMALS. 



1. Proteiika. 

 b. No branchisB or branchial clefts in the adult ; eyelids present; 

 carpus and tarsus more or less ossified ; vertebrte coinn?only 

 opisthocoelous. 



2. Salamandridea, 

 B. Limb? absent, o r all four present. Three large pectoral osseous 

 plates and an armor of small scutes on the ventral suTfiic<" 

 of tlie body ; vertebrae amphiccelous ; walls of the teeth more 

 or less folded. 



n. Lahyrinthodonta, 

 B. Tail obsolete in the adult. 



A. Limbs absent; numerous minute dermal scutes imbedded in 

 the integument of the serpentiform body. 



III. G^mnophiona. 

 £. All four limbs present, and the proximal elements of the 

 tarsus much elongated ; the body short, and the integument 

 devoid of small scutes, though dermal osseous plates are 

 sometimes developed in \K 



IV. Batrachia or Anura. 



The inlegntnent in most Amphibia is soft and moist, as in 

 the Frog, where numerous glands open upon its surface. The 

 Gymnojyhiona are exceptional, among existing Amphihin^ 

 in possessing small, rounded, flexible scales, like the cycloid 

 scales of fishes, imbedded within the wrinkled integument. 



In certain Batrachia ( Geratophrys dorsata, Ephippifer 

 cmrantiaous), flat dermal bony plates are developed in the 

 dorsal integument, and become united with some of the sub- 

 jacent vertebrtB. Many of the extinct Labyrinthodonta, and 

 probably the whole of the members of that group, possessed 

 an exoskeleton which appears to have been confined to the 

 ventral surface of the body. Under the anterior part of the 

 thorax there is a sort of plastron composed of one median and 

 two lateral plates. The median plate is rhomboidal. The 

 lateral ones are somewhat triangular, and unite with the 

 anterolateral margins of the median plate by one side, sending 

 a process upward and backward from their outer angles. 

 The outer surfases of all these plates exhibit a sculpture, which 

 radiates from the centre of the median plate and from the 

 outer angles of the lateral plates. These plates are in close 

 relation with the pectoral arch, and probably represent the 

 interclavicle and clavicles. 



Minute bony plates cover the surface of the throat in a 

 small African Labyrinthodont, Micropjholis. I have not met 

 with dermal ossicles in this position in otlier Labyrinthodonts. 



