REPORT ON THE ANATOMY OF THE PETRELS. 13 



The scutellation of the tarsi presents different characters in the Procellariidaa and 

 Oceanitidae respectively. In the former, in all the forms, the legs, which are often much 

 compressed below the lower limit of feathering, are covered pretty uniformly hy small 

 scutellaa of hexagonal shape {vide PI. I. fig. 5, a). In the Oceanitidae, on the other hand, 

 though the back and more or less of the lateral aspects of the leg are so covered, the 

 front of the leg is either, as in the genera Oceanites (PL I. fig. 1, a) and Fregetta 

 (PI. I. fig. 4, a), " ocreate," being covered for nearly all its length by a single long scute, 

 or, as in Garrodia and Pelagodroma (figs. 2, a; 3, a), has a series of strong, well- 

 marked, obliquely transverse scutellse, extending on to the external and internal faces 

 of the leg for some distance. 



The hallux in the Tubinares is always extremely small, and in the genus Pelccano'ides 

 quite absent. When present it consists only of a single joint (vide infra, p. 53, and 

 PI. VI. fig. 14), which, even when best developed, is very small and covered by a short, 

 nearly straight, spur-like claw, which projects externally, some little way above the 

 level of the other digits, and, being very small, may easily be passed over. In the 

 Oceanitidae this nail is extremely minute, considerably more so than in the Procellariidse 

 of similar size, but is always present 1 and very straight and spur-like. In most of the 

 Procellariidse it is larger and more curved : it is best developed proportionately, perhaps, 

 in Pagodroma. 



In the Albatrosses the hind-toe is so minute that these birds are usually described as 

 1 icing three-toed, but this is not really quite cor- led 

 rect. In Phcebetria the hallux externally only c ^ Q & 



just appears, being represented merely by a 

 .slight pimple-like elevation, with a very minute 



claw. On dissecting away the skin, the pimple T 



is seen to be connected with two minute bony 

 nodules, the basal one. which represents the 



metatarsal, more globular, the apical One more FlG - 2. -Rudimentary Hallux of the Albatrosses, of the 



natural size, except a. 



pointed and covered by the minute claw. a , Phwld/ . ia fttUgi . outside the skin 

 They are only connected by connective and nosa > sh ° win g the (represented in sec- 



. oi two ossicles, con- tion). 



fibrous tissue to the tarso-metatarsus,- and are nec ted together by 6> Dicmedea exuians. 



separated from each other by a considerable J^ 1 ™ 8 ^\ JJ" c . Diomedea h-achywa. 



interspace, the whole having a total extent of covered by a minute ,/. Thaltusiarche cul- 



only 3 mm. (vide fig. 2, a). ,law - wllich a w ,ears ""'""'"• 



In Thalassiarche (culminata) and Diomedea (brach yura and exulans) this hallux is 

 .still more rudimentary, and there is not a trace of a nail outside. Still, on careful 



1 Mr. Dresser erroneously describes it as wanting in Oceanites (Birds of Europe, vol. viii. p. 503). 



2 The existence of the rudimentary hallux in Phtebetria fuliginosa was first, I believe, pointed out by Dr. Kidder 

 in his account of the birds of Kerguelen's Land, Bull. U. S. Xat. Mus., vol. i. p. 22. 



