PRE-JURASSIC TETRAPODS. 



181 



Family Rhynchosaurid^e. 

 With plate-like pelvis. 



Rkynchqsaurus Owen. U. Trias, England. 



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

 Stenometopon Boulenger. M. Trias, Scotland. 

 ? Palacrodon Broom. M. Trias, S. Africa. 



Order Proganosauria Banr. 



Aquatic reptiles with long tails. Skulls elongated. Vertebrae 

 with small notochordal centra and very heavy arches and no 

 intercentra. A single coracoidal element, five distal carpals and 

 tarsals. Pelvis plate-like. 



Mesosaurus 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 coracoidal element and a plate-like 

 pubis. 



There is not the slightest evidence that the series of small 

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

 Williston believes Arceoscelis to be related to the lizard ancestry. 

 Broomia may also have affinities with the Squamata. Adelosaurus 

 may be related to the Rhynchocephalia. 



? Protorosaurus Meyer. IT. Permian, Germany and England. 



„ j Arceoscelis Williston. Artinskian, Texas. 



" [ Kaclaliosauriis Credner. L. Permian, Saxony. 

 I Broomia Watson. M. Permian, S. Africa. 



? < Heleosaurus Broom. ,, „ 



[ Heliophilus ,, ,, ,, 



? Adelosaurus Watson. U. Permian, England. 



lAphelosaurus Gervais. L. Permian, Autun. 



Notes on the Amphibian Classification. 



The superordinal separation of the Labyrinthodontia, Phyllo- 

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

 members of these groups differ 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 parasphenord with which the pterygoids are suturally 

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



