220 ANNALS NEW YORK ACADEMY OF SCIENCES 



comparisons between the pectoral paddles of Polypterus and the fore 

 limb of Urodeles until the phylogenetic relations of Polypterus to the 

 Devonian Osteolepida and of the latter to the Amphibia has been evalu- 

 ated, at least provisionally. Similarly, no homological value should be 

 attached to the limb-like form and functions of the paddles of Ceratodus 

 until the relationship of the latter to the Devonian Dipnoans and Osteo- 

 lepida has been taken into account. That the Dipnoi are related to the 

 Osteolepida is indicated especially by the agreement in certain histologi- 

 cal characters of the teeth and scales, in the character of the median and 

 paired fins, etc. If the Amphibia came off from this Pre-Devonian 

 Osteolepid-Dipnoan stem, the hiatus in both the geological record and in 

 the evolutionary sequence is a great one. I feel that there was cumula- 

 tive evidence for the view that the Amphibia has been derived from fishes 

 of some sort and more particularly that these fishes possess the following 

 characters : functional gills and "lungs," homologous with those of Dipnoi 

 and Crossopterygii, chondrocranium covered with bones having the same 

 ultimate derivation as the scales, skull elements very largely correspond- 

 ing with those of Ganoids but probably independently evolved, opercular 

 bone reduced or absent, preoperculum giving rise to the true squamosal 

 of Tetrapods (overlapping the quadrate), hyomandibular large, giving 

 rise to the columella auris, scales without ganoine, primary shoulder 

 girdle and pelvis becoming bony, body short, head large depressed, noto- 

 chord persistent, fore and hind paddles similar in form and function, 

 median and caudal fin reduced. A detailed comparison of the shoulder 

 girdle and pectoral paddle of one of the Ehizodonts, the Sauripterus of 

 Hall, with those of other fishes and Tetrapods leads to the following 

 provisional comparisons : 



Sauripterus Tetrapod 



"Infraclavicle" (clavicle of Oegenbaur) Clavicle 

 "Clavicle" (Cleithrum of Oegenbaur) Cleithrum 



Scapulo-coracoid Scapulo-coracoid 



Single "basal piece" Humerus 



"Basals" collectively Fore arm and carpus 



"Radials" collectively Digits 



In view of the marked differences, however, in the skull between the 

 Rhizodonts and the Amphibia, we cannot say whether these resemblances 

 are convergent or homogenetic. The paper was illustrated with lantern 

 slides. 



The Section then adjourned. L. Hussakof, 



Secretary. 



