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Show 1899.] OSTEOLOGY OF THE TUBINARES. 401 In Majaqueus and Diomedea exulans, for instance, the 2nd phalanx of digit II. exceeds that of the 1st. Phalanx i. of digit I. is equal in length to that of phalanx i. digit II. In Diomedea again it is rather less instead of equal. In the smaller Petrels the elongation of these phalanges is not so marked. ix. THE PELVIC LIMB. The bones of tbe pelvic limb are non-pneumatic ; the tibio-tarsus is characterized by an enormous flabelliform ectocnemial crest which rises high above the articular surface for the femur: is markedly inflected at its distal end, and provided with an ossified extensor bridge. The fibula does not extend more than § the way down the leg, and is much reduced in thickness distally. The tarso-metatarsus has a well-marked intercondylar tubercle. The hypo-tarsus is complex in the Procellariidas and simple in the Diomedeidas. The outer and middle toes are of equal length. In one skeleton of Diomedea exulans I find an ossified tarsometatarsal extensor bridge on the right foot. The hallux is represented by a metatarsal and an ungual phalanx, the latter often of considerable size. In Pelecanoides it is absent. The femur, as a rule, is about as long as, or less than, the tarso-metatarsus, and is about half as long as the tibio-tarsus ; in Oceanites, Pelagodroma, Cgmodroma, and Procellaria the femur shortens conspicuously, these measurements being about i as long as the tarso-metatarsus and ^ as long as the tibio-tarsus. x. RESULTS. Briefly, I think, the outcome of this paper has been to confirm, in a large measure, the conclusions of Forbes as set forth in his most valuable Eeport on the Petrels collected during the ' Challenger' Expedition (5). The appended diagram (fig. 2, p. 402) is a modification of that published by him in that work. H e divided this suborder into two families-PROCELLARIIDJE and OCEANITID^E; and two subfamilies-PROCELLARIINJ<: and DIOMEDEIN^E. Pelecanoides he regarded as an aberrant genus of the first mentioned subfamily. I propose to make two Families-the PROCELLARIID^; and the DIOMEDEID^E ; the former being further divided into two subfamilies- PROCELLARIINJE and PELECANOIDIN^. Thus Forbes's D I O M E D E I N ^ E becomes raised to the rank of a family, his genus Pelecanoides to the rank of a subfamily, whilst his family OcEANiTiDiE becomes, in m y scheme, reduced to a section of the PROCELLARIINJE. The sections in this subfamily are three in number, and can quite conveniently be diagnosed from the characters of the skull alone (see Keys, pp. 403-409). Pelecanoides forms the second subfamily. In the great Avidth of the basitemporal region of its skull it differs from every other member of the suborder. The sternum and pectoral girdle are |
