REPORT ON THE ANATOMY OF THE PETRELS. 



59 



Daption) on the cue hand, and with the Fulmars on the other, Aeipetes* being the 

 less specialised of these, both as regards its imperfect tracheal septum, and the number 

 of rectrices. The type of syrinx so characteristic of the Fulmars is foreshadowed, a.s it 

 were, as has been already pointed out (supra, p. 35) in that of Pagodroma, and all 

 four genera (Fulmarus, Thalassceca, Ossifraga, and Aeipetes) agree in the general 

 disposition of the tensor patagii, which has no ossicles, in the more or less rudimentary 

 os uncinatum in the tendency to anchylosis of the lachrymal and frontal, in the shape 

 of the tongue and of more or less well-developed lamellae on the bill, and in having four 

 more or less complete, but never deep, sternal emarginations. 



Aeipetes is, on the whole, the least specialised of the Fulmarine group in the most 

 limited sense. This includes besides Thalassceca, Fulmarus, and Ossifraga, which last, 



a, 



s& 



Fig. 32. 



Fig. 31. — Beak of TJialassaca glaciahidcs. a. The aperture of the nasal tubes, 



from in front. Natural size. 



Fio. 32. — The same parts of Aeipetes antarcticus. 



on account of its great size, peculiar syrinx, and sixteen rectrices, may be considered the 

 culminating point in this direction of the Procellariidae. 



The remaining genera, CEstrelata, Puffinus, Adamastor, Majaqueus, and Bulweria 

 are also apparently closely related to each other, the first and last named being perhaps 



1 I propose to make a germs under this name, for the reception of the Proeellaria antarctica of Gmelin (Syst. Nat., 

 17S8, vol. i. p. 565), which has usually been considered congeneric with Thalassceca, the type (and only representative) 

 of which is Thalassceca glacialoi3.es. For the latter bird also was instituted Hombron and Jacquinot's genus Priocella 

 (s.c, vol. iii. p. 148). Aeipetes is easily distinguishable from Thalassceca by the much shorter and stouter bill, and 

 differently shaped nasal tubes, as will be best understood from the accompanying figures (figs. 31, 32). The number 

 of rectrices is also different (twelve as compared to fourteen) ; the tracheal septum is incomplete, and the structure of 

 the syrinx also quite different {vide supra, p. 37). The coloration of the two forms is quite unlike. 



