400 Prof. W. K. Parker. Amphibian and Reptilian [Feb. 23, 



a small remnant of the "guard" right and left, or two "basitem- 

 poral " plates, soon buried up by the huge pterygoid. 



In all birds they are large, as large as in Frogs and Toads ; 

 this is equally true of the Dinomis and of the smallest Humming- 

 bird. 



There is a tendency to break up into lesser bony parts ; thus for a 

 day or two in the chick there are two " basitemporal " and one 

 " rostra] " centre ; but in several species of the Ranidge, e.g., the Bull- 

 frog among others, the point of the dagger-shaped bone is separately 

 ossified, and remains distinct. 



In the Paradoxical Prog (Pseudis paradoxa) there is no "handle" 

 to the dagger ; the same form of parasphenoid is common among the 

 water-birds, e.g., Aha, TJria. This is an ossification which is the 

 earliest to appear in skulls that take on any kind of ossification ; it 

 is also the first bone to appear in an embryo bird, as in the larval 

 Prog. 



These facts, and many others that I could mention, make it evident 

 that in seeking for a clue to the uprise of the Feathered Fowl, we 

 may leave out of immediate consideration all the existing types of 

 Reptilia : ancient Amphibians, or Reptiles just rising out of Amphibian 

 lowliness, are the forms that alone will help us in this search. 



We do get some light upon the Reptilian relationship of Birds, 

 but it is at best a scattered light; the head of a bird is like that of the 

 Ichthyosaurus, in its great facial elongation, the neck- and limb-regions 

 of a Bird are those of a Plesiosaurus, whilst the hips and legs are 

 like those of the " Ornithoscelida." 



Scarcely any Urodeles, and only a few of the Anura, show any 

 special elongation of the " intertrabecula " or pre-nasal rostral car- 

 tilage ; this must have been very long in the Ichthyosauri as in the 

 Selachians, and as in the embryos of all Birds. 



In the Tadpole, with its oral aperture in front of the head, the 

 quadrate cartilage or suspensorium of the lower jaw is parallel with 

 the fore part of the basis-cranii, or trabecular. During transforma- 

 tion the quadrate hinge gradually gets further and further back 

 until, in the Bull-frog, it is beneath the neck, close to the shoulder. 

 The pterygo-palatine arcade, which was a mere connecting band 

 between the quadrate and the trabecula, becomes the long palato-ptery- 

 goid arch or arcade, and the fore part of it is tri-radiate, and has 

 received a term for each ray. 



Thus the suspensorial part or pedicle is the ethmo-palatine, the 

 anterior free spike the pre-palatine, and the hinder part which runs 

 into the pterygoid is the post-palatine. 



The anterior part of the pterygo-palatine arcade is distinct from 

 the pterygoid in the Salamanders and their allies — Urodeles — and 

 the pterygoid in them is an outgrowth of the quadrate which grows 



