440 Geological Society. 



conveyed directly into the embryo-sac by the channel of the pollen- 

 tube ; a similar process appears to exist in the conjugation of some 

 of the lower Algse ; in other cases the spermatic fluid is conveyed 

 from organs situated at a distance from the parent-cell of the germinal 

 vesicle by the agency of the locomotive structures (spermatozoids) 

 developed in the spermatic cells, bathed in and discharged with their 

 contents, and themselves composed of the nitrogenous protoplasmic 

 matter of cell-contents." A series of thirty-six clever microscopic 

 figures was given in illustration of the memoir. 



GEOLOGICAL SOCIETY. 



February 20, 18.56. — D. Sharpe, Esq., President, in the Chair. 



" On the Affinities of the great extinct Bird (Gastornis parisi- 

 ensis, Hebert) from the lower Eocene near Paris." By Prof. Owen, 

 F.R.S., F.G.S. 



Prof. Owen communicated the results of his comparisons of the 

 fossil tibia of the Gastornis parisiensis, Hebert, — a large bird from 

 the lower Eocene deposits at Meudon near Paris — with the tibiae of 

 known recent and fossil birds. 



The tibia of the Gastornis presents the same median position of 

 the supra-tendinal bridge as in the Albatross and the lamellirostral 

 web-footed birds ; but, as the same position of the bridge occurs in 

 the Notornis, the Gallinule, the Raven, and some accipitrine birds, 

 that character is not conclusive of the affinities of the Gastornis to 

 the Palmipeds ; and it is further invalidated by a difference in the 

 aspect of the plane of the lower outlet of the bridge. In the Alba- 

 tross (Diomedcea) and the Lamellirostres, the foramen or outlet looks 

 directly forwards ; its plane is vertical. In the oblique aspect of 

 that outlet, the Gastornis more resembles the large Waders (GrallcB) 

 and the Dinornis tribe. Amongst the Gallinacece, the Turkey {Me- 

 leagris) nearly resembles the Gastornis in the position of the bridge ; 

 and more nearly resembles it than does the Albatross or the Swan in 

 the low tuberosity external to the bridge above the base of the outer 

 condyle, as well as in the shallow groove dividing that tuberosity 

 from the bridge. The depression on the fore-part of the tibia above 

 the distal condyles, if natural to the Gastornis, is a structure not 

 precisely repeated in any of the Grallae. In the Ciconia Argala the 

 anterior interspace of the condyles forms a cavity, bounded above by 

 the tubercle and ridge developed from the bridge, and by the oblique 

 converging upper borders of the condyles below. The canal of the 

 bridge opens below into the concavity. In the Grus Antigone the 

 lower border of the outlet of the bridge defines, with a tubercle ex- 

 ternal to it, the shallow supracondyloid cavity; but there is no 

 definite fossa, like that in the Gastornis. 



In the Notornis, the breadth of the lower end of the tibia a little 

 exceeds the depth or fore-and-aft diameter of the condyles. The 

 supra-tendinal bridge is of moderate breadth, is transverse, and median 

 in position ; its lower outlet looks forward just above the wide and 

 shallow intercondyloid space. The extinct Aptornis chiefly differs 

 from the Notornis in the less median position of the bridge, and in 



