[CHAPTER X.]
ORDER CAUDATA DUMÉRIL, 1806. COAL MEASURES TO RECENT.
Naked-skinned, elongate, tailed salamanders, mud-puppies, efts, newts, etc. External gills present or absent in adult condition, but always present in young. Limbs short, with usually 4 digits on hand and 5 on foot, but this is subject to much difference. Limbs never very stout. Carpus and tarsus cartilaginous. Skull roof without the postparietal, postorbital, and supratemporal. Skull elements never ornamented and never cut by the lateral-line canals. Vertebræ consisting of a single element; ribs short, attached to an elongate transverse process. Caudal ribs seldom present. Parietal foramen lacking. No ventral armature. Fresh-water inhabitants.
Suborder PROTEIDA Cope, 1868.
This order agrees generally with the Caudata, but presents one most important feature of difference in the presence of the opisthotic. It is this point which gives the Proteida its intermediate position between the extinct amphibians and the recent species, and seems to indicate a connecting line from the Coal Measures down to the present. The structure of the hyobranchial arches sustains this view.
The hyoid apparatus differs from that of other adult Caudata and resembles that of their larvæ in having three epibranchials, instead of one only. The second basibranchial is also connected with the first, which is not the case with the other Caudata. Three extinct genera are placed tentatively in this suborder.
Family COCYTINIDÆ Cope, 1875.
Cope, Bull. U. S. Nat. Mus., No. 1, p. 12, 1875.
The present family, as here defined, includes the forms whose structure seems to ally them with the modern salamanders. The character on which most dependence is placed is that of the branchial apparatus, lacking in Hyphasma. The forms are all incompletely known and the family will doubtless require revision on acquisition of additional material. Three genera, each with a single species, are: