18 Mr. W.S. Macreay on the Comparative Anatomy 
The following table relates to the variation in number of the 
dorsal vertebrze, or those to which the ribs are attached. 
Number | Maximum num-| Minimum num-| Extent 
Orders. of species| ber of dorsal ber of dorsal of Observations. 
examined. vertebra. vertebra, variation. 
1. RaptoreEs. . 8 7 
Pandion, Vultur. 
2. INSESSORES . 2 9 6 
Fringilla. Loxia. 
8. Rasores .. 11 igen 
Casuarius. Meleagris. 
4, GRALLATORES 9 7 
Grus. Ciconia. 
in the Linnean Transac- 
tions, Tachypetes Aquilus 
has seven ribs. 
5. NaTATOREs . 11 (i 
Cygnus. Pelecanus. 
oe: to Mr. Burton 
Here the variation is least in the Raptores, and greatest in the 
Rasores and Natatores; where again, by the bye, it is worth 
noticing, that the Swan and Cassowary agree in possessing the 
maximum number of ribs which the whole class of birds pre- 
sents. 
We now come to a table of the variation in number of the 
sacral vertebra, founded on the same data; which table, how- 
ever, is less perhaps to be depended upon than the others, in 
p- 154, in speaking of the genera Diomedea and Phaeton, he observes, that they appear 
“non inter se modo cognati ob longissimas alas, altissimum volatum et vivendi ra- 
tionem, sed et Pelecano Aquilo conjuncti eandem ob causam, unde in eadem tabulze 
lineé juxta-positi et cum Fulcone Haliato simili modo in pisces quibus victitat ex alto 
irruente conjuncti.” I was much pleased, when off the coast of Martinique, to behold 
the Tachypetes floating over the Diamond Rock just like an eagle. The sailors assured 
me, that he often seizes his prey with his talons; and on referring to the Histoire 
Naturelle et Morale des Iles Antilles de l’ Amerique, published in 1658, where there is 
a very detailed account of the Fregates, I find the following passage :—“ Ils se placent 
si bien du costé ou les poissons volans doivent faire leur saillié que dez qu’ils sortent 
de l’eau ils les regoivent en leur bec ou en leurs serres.” p. 148. 
consequence 
