408 MB,, w. p. PYCKAFT ON THE [Mar. 21, 



b. Size larger, not less t.han 2J in. {Sulweria alone excepted) ; postacetabular 

 ilium with dorsal border well-defined and terminating in a well-marked 

 spine. 

 c'. Pre-ilium moderately broad and expanded distally, resting upon the 

 synsacrum and partly concealing it; ischium having its free end more 

 or less sharply deflected. 

 e". Post-ilium with flattened dorsal aspect, rapidly tapering to form a 

 laterally-compressed blade-like edge, terminating in a spine ; obtu- 

 rator foramen an elongated oval twice length of the acetabulum ; 

 free end of ischium bent at right angles to long axis, narrow and 



tapering to a point Puffimcs. 



Majaqueus. 



f". Post-ilium slightly or not at all compressed dorsally ; pubis projecting 

 distinctly beyond the ischium ; ischium with broad flattened foot 

 closely articulatiug with pubis, 

 c^. Ischiadic foramen nearly circular ; dorsal border of pre-ilium 

 concave. 

 e*. Width of dorsal aspect of post-ilium rapidly decreasing from 

 before backwards ; post-iliac spine ill-defined ... Thalassceca. 

 d*. Width of dorsal aspect of post-ilium broad throughout ; post- 

 iliac spine well-defiued Priocella. 



d?. Ischiadic foramen oval ; dorsal border of pre-ilium straight, 

 e*. Thoracic vertebra immediately in front of pre-ilium fused with 

 synsacrum. 



a?. Entire length of pelvis not less than 3^ in Fulmarus. 



b^. Entire length of pelvis not exceeding 2^ in Baption. 



e^. Lumbar enlargement forming a distinct tumid swelling in front 

 of acetabulum. 

 /*. Ischium never completely fused with pubis posteriorly. 



c^. Anterior border of pre-ilium obliquely truncated ; ischium 



tapering to a fine point CEstrelata. 



d^. Anterior border of pre-ilium squarely truncated ; ischium of 



equal width throughout Bulwcria. 



g'^. Pubis completely fused posteriorly with ischium ... Prion. 

 d'. Pre-ilium reduced to narrow bars, separated one from another by the 

 whole width of the synsacrum ; ischium in the form of a long slender 

 spine running directly backwards Pelecanoides. 



B. Pre-ilia meeting in the mid-dorsal line above the synsacral neural crest ; 

 suture dividing innominate bones from synsacrum almost or quite ob- 

 literated. 



a. With a more or less well-marked pectineal process ; free end of ischium 



turning downwards in a strong curve; pubis of uniform thickness 

 tliroughout; cavity of pelvis not divided into anterior and posterior 

 renal fossse Vssifraga. 



b. No pectineal process ; free end of ischium not abruptly curved ; cavity of 



pelvis distinctly divisible into anterior and posterior renal fossaj ; ribs 

 of saci-al vertebraj extending across renal cavity immediately behind 

 acetabulum JDiomedea. 



E. Pectoral Limb. 



Humerus with a shallow coraco-humeral gi'oove ; a triangular pectoral crest 

 not extending far down the shaft ; crista inferior very small, formed for the 

 most part by the downwardly-directed tuberculum inferius ; with a large ect- 

 epicondylar process, and a more or less deep fossa for tlie brachialis internus ; 

 the sub-trochantenc fossa is in no ease of more than medium size, and never 

 subdivided into two ; the ulna is without an olecranon process ; the phalanx of 

 the poUex and the 2nd phalanx of Mc. II. are of great length. 



