CARBONIFEROUS PERIOD. 345 



of the Mesozoic. Kemains of three or four of the Reptiles were 

 found at the Joggins in Nova Scotia, in the interior of a Sigillaria 

 stump, which had become partly hollowed out by decay and after- 

 wards filled by sand and mud in the marsh or forest where it stood, 



Salamandrids. — Species without gills or gill-openings in the adult state. 



In most of the North American Salamandrids there are teeth on the vomer, 

 and no parotid gland; while the species of Europe want these vomerine teeth, 

 and have parotid glands. 



3. Batrachoids (so named from the Greek 0arpaxog, a frog), or Batrachia 

 Anonra. Body having four long legs (the hinder the longer) and no tail; as 

 in the toads and frogs. The teeth are small, and mostly on the roof of the 

 mouth on the vomer, with none in the lower jaw; the vertebra? are typically 

 ten, but sometimes coalesce so as to appear fewer, the apparent number seldom 

 exceeding eight ; the ribs are wanting. 



4. Labyrinthodonts. — The species of this group of extinct Amphibians re- 

 semble the Batrachoids in having (1) double occipital condyles; (2) teeth on 

 the vomer; (3) short, if any, ribs; (4) usually large palatine openings: and 

 they approach Saurians in having (1) the teeth stout and conical, and set in 

 sockets; (2) the body covered with plates or scales; (3) the size sometimes very 

 great. The teeth have the labyrinthine arrangement of the dentine and cement 

 that characterizes the Sauroid fishes among Ganoids (see fig. 481), and which 

 is still continued in that group among the living Gars ; and hence the name 

 Labyrinthodonte. 



The Ganocephala are supposed by some to be related to the inferior Sala- 

 mandroids, while approaching Ganoid fishes in the sculptured bony plates which 

 covered the head, and in some other characters. — Ex., Archegosaurus and Apateon. 

 Agassiz considers them, on good grounds, true Ganoids. 



II. True Reptiles. 

 The skeleton in the true Reptiles has (1) but one occipital condyle below the fora- 

 men ; (2) a series of ribs ; (3) a covering of scales or plates, with rare exceptions. 

 The existing species, and part of the extinct, belong to three tribes : — 



1. Snakes, or Ophidians. — (1) Body without legs with rare exceptions; (2) 

 no sternum ; (3) eyes without lids ; (4) no external ear. 



2. Satjrians. — Body (1) without a carapax and with a tail ; and having (2) 

 four feet (rarely two, or none); (3) a sternum corresponding to two united verte- 

 brae, sometimes more; (4) eyes with lids, or seldom without; (5) usually an ex- 

 ternal ear-opening. 



3. Turtles, or Chelonians. — Body having (1) a carapax, or shell, made of 

 several pieces firmly united; (2) a very large sternum forming the under surface 

 of the body ; (3) a horny beak instead of teeth ; (4) an external ear-opening ; (5) 

 neck and limbs very flexible. The Chelonians have many marks of superior 

 rank. But the species appear to be analogous to birds among the higher verte- 

 brates, or the bats among mammals, — that is, inferior in grade, because they are 

 of a small type or life-system, such as are styled microsthenic in the remarks on 

 Mammals. (See under the Triassic period, p. 421.) 



