671 



Crossopterygians and I fully agree with Gill, when he places the Di- 

 pnoi with the Teleostomi, and with Jaekel when he divides the Gna- 

 tosthomatous Fishes into two large groups the Anossei (Elasmobranchii) 

 and the Ossei (Teleostomi). 



When we shall have found Batrachia in the Devonian, we shall 

 know whether the opinion of the Crossopterygian ancestry is correct. 

 Batrachia must have existed during the Devonian ; for already in the 

 Carboniferous the Stegocephali are differentiated into forms with and 

 without limbs. There are only two genera of the Crossopterygia living 

 to day; both are confined to Africa: Polypterus and Calamo- 

 ichthys. If the development of the skeleton could be studied in 

 Polypterus for instance, certainly some interesting points could be 

 found out. 



This lecture was given before the Biological Club of the Univer- 

 sity of Chicago, April 10th 1895. It is printed now in the original 

 form, with the single exception that the results of Gegenbaur on the 

 clavicle and Cleithrum have been added. In the original I had only 

 discussed the clavicles and in tercla viele, omiting the cleithrum, since 

 I had doubts about its true nature. When I returned from my pa- 

 laeontological trip to Wyoming September 18th. I found among my 

 mail an excellent paper by my friend Louis Dollo „Sur la Phylog^nie 

 des Dipneustes"; in which he reaches exactly the same results about 

 the ancestors of the Batrachia especially through a very interesting 

 study of the caudal fins of the Dipnoi and Crossopterygii. 



8ome of the more important literature connected with this paper: 



Allis, Edw. Phelps, The Anatomy and Development of the lateral line 



System in Amia calva. With 16 cuts and 13 pi. Journ. Morphol., 



Vol. II, No. 3, p. 463 — 568. 1889. 

 Andrews, C. W., Note on a Specimen of Keraterpetum Galvani, Huxley. 



Geolog. Mag., Dec. IV, Vol. II, No. 368, p. 81—84. (fig.) February 



1895. 

 Baue, G., Ueber die Morphogenie der Wirbelsäule der Amnioten. Biol. 



Centralbl., Bd. VI, No. 11 and 12, 1886, p. 332—342; p. 353—363. 



— — Beiträge zur Morphologie des Carpus und Tarsus der Vertebraten. 

 I. Teil. Batrachia. Jena 1888. 86 pp. 3 pl. 



— — Palaeohatteria, Cbednee and the Proganosauria. Am. Joum. Soc, 

 April 1889, p. 310—311. 



— — Kadaliosaurus priscus, Ceedneb, a new Reptile from the lower 

 Permian of Saxony. Am. Journ. Soc, Febr. 1890, p. 156 — 158. 



— — On the morphology of the Vertebrate Skull. Journ. Morphol., 

 Vol. Ill, 1889, p. 467—474. 



