1899.] OSTEOLOGY OF THE TT7BI?fAUES. 409 



A. Humerus non-pneumatic ; crista inferior never inflated along its free edge. 



l'roceUariid<s, 



B. Humerus pneumatic; crista inferior inflated along its preaxial border; 



sub-trochanterie fossa small, receiving several pneumatic forumiua. 



BiomedeidcB. 



F. Pbltio Limb. 



All the bones non-pneumatic ; tibio-tarsus vr ith a greatly enlarged ecto- 

 cnemial crest foriuing a large flabelliforin crest rising liigh above the articular 

 surface ; with an extensor bridge ; outer and middle toes of equal lenglh ; 

 hallux more or less vestigial ; tibio-tarsus with a more or less well-marked 

 intercotylar tubercle; 1st phalanx of D. II. = to or longer than that of 1). III. 



A. Hypotarsus complex ProceUariidcs. 



a. Tarso-uietatarsus longer than the outer toe. 



a'. Ungual phalanges flattened; basal phalanx of middle toe as long as or 

 longer than next two taken together {Forbes), 

 a". Tarso-metatarsus markedly longer than the outer toe, grooved an- 

 tei-iorly throughout, its length = ^ that of the tibio-tarsus ; ph. 1 



of D. II. lunger than ph. 1, D. III. & IV Ct/niodroma. 



b". Tarso-metalarsits much longer than outer toe ; trochlea all in same 

 plane ; grooved anteriorly, much flattened distally autero-pos- 

 teriorly ; o toes nearly = ph. I. D. II. & III., = longer than IV. 



Freffetta. 



c". Tarso-metatarsus longer than outer toe, f as long as tibio-tarsus ; 



fibular riilge scarcely longer than the width across the proximal 



articular surface of the tibio-tarsus ; basal phalanges of D. II. and 



III. = and longer than that of IV Oceanites. 



d", Tarso-metatarsus much longer than the outer toe, | as long as tibio- 

 tarsus, with a shallow groove throughout its whole length ; basal 

 phalanges D. II. and Ill.^and longer than IV. ; outer and middle 



toes equal Pelagodronia. 



b'. Ungual phalanges pointed ; basal phalanx of middle toe shorter than 

 next two joints (Forbes). 



e". Tarso-metatarsus only slightly longer than the outer toe; fibular 

 ridge obsolete Frocellaria. 



b. Tarso-metatarsus shorter than outer toe, but much longer than femur. 

 c'. Fibular ridge obsolescent. 



/". Tarso-metatiirsus faintly grooved anteriorly, its outer border raised 



into a sharp ridge , Fuffinus. 



g" . Tarso-metatarsus deeply grooved anteriorly, outer border not con- 

 spicuously developed Bidweria. 



d\ Fibular ridge distinct. 



h". Tax'so-metatarsal groove nearly obsolete { Baption, 



\ Prion. 

 i". Tarso-metatarsus grooved anteriorly and posteriorly ... iEstrelaia. 

 j"- 



a^. Groove deeper, length not exceeding 2^ in Majaquens, 



b'^. Groove shallower, length not less than 3f in Ossifraga. 



c. Tarso-metatarsus shorter than outer toe, scarcely longer than femur. 



k". Tarso-metatarsal groove obsolescent, hallux present. 



6-'^ Ectocnemial crest stronger; shaft of tibio-tarsus nob exceeding 



3^ in Thalassmca. 



d^. Ectocnemial crest weaker ; shaft of tibio-tarsus not exceeding 



3f in Priocella. 



I". Tarso-metatarsal groove obsolescent ; hallux absent ... Pelccanoides. 



B. Hypotarsus simple ; ectocnemial large, forming an acute angle with the 



entocnemial crest proximally ; fibular ridge scarcely raised above kaif of 

 shaft Biomedeidce. 



