PRE-JURASSIC TETHAPODS. 181 



Family Rhynchosaurid^. 

 "With plate-like pelvis. 



Rhynchosaunis Owen. U. Trias, England. 

 Hyperodapedon Hux. M. & U. Trias, England, Scotland, India. 

 Stenometopon Boulenger. M. Trias, Scotland. 

 '^. Pcdacrodon Broom. M. Trias, S.Africa. 



Order Proganosauria Baur. 



Aquatic reptiles with long tails. Skulls elongated. Yertebrse 

 with small notochordal centra and very heavy arches and no 

 intercentra. A single coracoidal element, five distal carpals and 

 tarsals. Pelvis plate- like. 



Mesosauri(jS Gervais. L. ? Permian, S. Africa, Brazil. 



Noteosaurus Broom. ,, S. Africa. 



Stereosternum Cope. ,, Brazil. 



Order Protorosauria Seeley. 



Lightly built reptiles with pointed skulls and a single tem- 

 poral vacuity. A single coiucoidal element and a plate-like 

 ptubis. 



I'here is not the slightest evidence that the series of small 

 Palaeozoic reptiles listed below are lelated to one another. Prof. 

 WillLston believes Arceoscelis to be related to the lizaixl ancestiy. 

 Broomia may also have affinities with the Squamata. Adeloscmrus 

 may be related to the Rhynchocephalia. 



? Frotorosaurus Meyer. U. Permian, Germany and England. 

 ' Arceoscelis Williston. Artinskian, Texas. 

 Kadaliosauribs Creduer. L. Permian, Saxony. 

 jBroomia Watson. M. Permian, S. Africa. 



Heleosaurus Broom. ,, ^^ 



Heliophilus ,, ,, ,, 



% Adelosauru.s Watson. U. Permian, England. 



'i.Aphelosaurus Gervais. L. Permian, Autun. 



JSTOXES ON THE AMPHIBIAN CLASSIFICATION. 



The superordinal separation of the Labyrinthodontia, Phyllo- 

 spondylia, and Lepospondylia is based on the fact tliat the early 

 members of these groups dilfer from one another as much as do 

 their ultimate descendants, despite the fact that in a number of 

 characters such as the gradual development of large interptery- 

 goid vacuities, the replacement of basipterygoid processes with 

 definite articulating surfaces by expansions of the posterior end 

 of the parasphenoid with which the pterygoids are suturally 

 united, and the loss of a finger in the hand, tJje course of 

 evolutionary change is the same in the first and last group. The 

 structure of the skull and lower jaw is known to be similar in 



