442 ON THE ANATOMY OF PODICA SENEGALENSIS. [JuUC 3, 



into these fosste. Perhaps also the comparatively great length of the 

 basis cranii is associated with this muscular development. 11' you 

 smooth down the skull of a Grebe and pare away the strongly 

 developed ridges, the result is not very unlike the skull of a Kail. 

 There are not any other really marked differences between the skulls. 

 Fiirbringer [4, p. 1029 et seq^] lays no weight upon the systematic 

 value of these characters ; he does not refer to them in his digest 

 of the important cranial characters. 



With regard to the other characters which the skeleton exhibits, 

 it is true that no resemblance is shown to the Divers and Grebes. 

 On the other hand, its resemblance to the Rails which has been so 

 insisted upon by Giebel is in my opinion less striking than its 

 differences from the same group of birds. 



Turning to the muscular anatomy, we have a mixture of Colymbine 

 and Ralline characters with a decided element that is peculiar to 

 the Heliornithidce. On the whole, if it were necessary to associate 

 Podica definitely with either of the two groups to which it 

 shows affinity, I should feel obliged to regard it as belonging to the 

 Colymbidse. 



Taking everything into consideration, it seems that the Heliorni- 

 thidce form a distinct familj- which has traversed for a certain 

 distance the branch leading from the Rails to the Colymbidte and 

 has then diverged rather widely in a direction of its own. 



List of Memoirs. 



1. Garrod, a. H. — On the Anatomy of Cliauna derbiana and on 



the Systematic Position of the Screamers (Palamedeidse). 

 Proc. Zool. Soc. 1876, p. 189 et seq. 



2. Garrod, A. H.- — On Certain Muscles of the Thigh of Birds, 



and on their Value in Classification. — Part II. Proc. Zool. 

 Soc. 1874, p. Ill et seq. 



3. Garrod, A. H. — ^^otes on the Anatomy of Plotus anldnga. 



Proc. Zool. Soc. 1876, p. 335 et seq. 



4. FtJRBRiNGER. — Uutersuchuugen zur Morphologic und Syste- 



matik der Yogel. Amsterdam, 1888, 



5. Gadow, H. — Aves, in Bronn's ' Thierreichs.' 



6. GrEBEi, C. — Zur Xaturgeschichte des surinamischen Wasser- 



huhns, Podoa surinameiisis. Zeitschr. ges. Naturw. Bd. xviii. 

 (1861) pp. 424-437. 



7. Brandt, .1. F. — Beitrage zur Kenntniss der N^aturgeschicte der 



Vogel etc. Mem. Ac. Sci. St. Petersbourg, 6*^ ser. t. iii. 1840, 

 pp. 81-239. 



8. ScHLEGEL, H. — Museum d'histoire naturelle des Pays-Bas, t. vi. 



9. ScLATER, P. L. — Remarks on the Fifth Cubital Remex of the 



Wing in the Carinat*. Ibis, 1890, p. 77. 



10. What, R. S. — On some Points in the Morphology of the Wings 



of Birds. P. Z. S. 1887, p. 343. 



11. Parker, W. K. — A Monograph on the Structure and Develop- 



ment of the Shoulder-girdle and Sternum in the Vertebrata, 

 Ray Society, 1868. 



