rarasphenoid of a PaUeoniscoid. 433 



ing this distinctive type of '' autostyly." This points very 

 strongly to an atiinity along tiiis line and to a derivation of 

 the Tetrapoda from some group of primitive Teleostomes. 



It is to be noted also that this characteristic " autostyly '' 

 we have traced, is not the "autostyly" of tlie Dipnoi, nor 

 does it agree with the condition in the Tetrapoda to which 

 that term is usually applied. In the former group the 

 quadrate region of the pahito-quadrate bar is directly fused 

 to the auditory capsule; in the latter the primitive mode of 

 attachment, as Watson has shown for Loxomma, BatracJiid- 

 erpeton^ &c., is for the quadrate region to come into 

 connexioHj not with the auditory capsule, but with the 

 dermal cheek-bones — the squamosals. 



We have tiierefore three distinct methods by which the 

 palato-quadrate bar has come to possess an " autostylic " 

 suspension, and, since this same term has been applied 

 indiscriminately to all three, considerable confusion exists in 

 consequence. 



The foregoing observations have thus supported two strong 

 arguments in favour of a primitive Teleostome, and against a 

 Dipnoan, derivation of the Tetrapoda: — 



(1) The compound para-basisplienoid bone has a similar 

 form in primitive Teleostomes and all primitive Tetrapoda, 

 while the corresponding bone of tlie Dipnoi is totally 

 different. 



(2) In both primitive Teleostomes and Tetrapoda the 

 palato-quadrate has a " pedicular "" autostylic suspension, 

 while tlie type of autostyly present in Dipnoi is not found in 

 Tetrapoda. 



References. 



(i) Traquair. " British Carboniferous Ganoid Fishes : Palieouiscidae '' 

 [Pal. Soc], p. 16, pi. ii. tig. 5. 



(2) Fritsch. • Fauna der Gaskohle uud der Kalksteine der Perm- 



formation Bcihrnens.' Band iii. Heft ii. p. 79, text-fig. 278 j 

 Band iii. Heft iii. 



(3) Swinnerton and Howes. " On the Development of the Skeleton 



of the Tuatara, Spheiiodon pioictatus." Trans. Zool. Soc. vol. xvi. 

 (1903), pp. 1-86, pis. i.-vi. 



(4) W. II. Parker. " On the Structure and Development of the 



Skull in the Common Snake (Tropidonotus natriv)." Phil. Trans. 

 Roy. Soc. 1878 (pt. ii.), pp. 385-417, pL«. xxvii.-xxxiii. 



(5) C. W. Andrews. ' British Museum Catalogue of the Marine 



Reptiles of the Oxford Clay.' Part I. pp. 12-16, text-tig. 7 ; 

 pp. 150-152, text-figs. 73 & 74. 



(6) D. M. S. Watsox. " The larger Coal Measure Amphibia." ^lem. 



& Proc. of the Manchester Lit. & Phil. Soc. vol. Ivii. (1912-13), 

 pp. 1-14, text-figs. 1 & 2, pi. i. 



(7) Fritsch. ' Fauna der Gaskolile and der Kalksteine der Perui- 



ibrmatiou Bohmens.' Ertter Baud, pp. 69 & 83, pis. iii. & ix. 



