98 MB. W. p. PTCBAFT ON THE [Feb. 15, 



F. Peltic Limb. 



A. Fibula never more than three-fourths as long as the tibio-tarsus. 



a. Femur with a deep popliteal depression : tibio-tavsus with moderately 



well-developed ento- and ectocnemial crests. Fibular ridge well-marked, 

 extending downwards to within a short distance of the middle of the 

 shaft. Tarso-ruetatarsus with a large pneumatic foramen on the inner 

 side of its proximal end : hypotarsus with a vertical ridge having a 

 moderate backward extension, the free edge of which is expanded iuto a 

 flattened surface ; on the outer .?ide of the ridge lie two closed canals : 

 with a deep fossa above the insertion of the tibialis anticus leading into 

 two large pneumatic foramina. Middle toe shorter than tarso-raeta- 

 tarsus Pelecanug. 



b. Femur without a popliteal depression : tibio-tarsus with feebly developed 



ecto- and eutocnemial crests. Fibular ridge absent. Tarso-metatarsus 

 deeply gi-ooved anteriorly, the groove leading directly into the foramen 

 between the third and fourth trochlea? ; gastrocnemial ridge feebly 

 developed. Middle toe longer than the tarso-metatarsus ... rhacthov. 



B. Fibula extending downwards to the level of the external articular condyle 



of the tibio-tarsus. 



c. Femur with a fossa at the base of the great trochanter into which 



numerous pneumatic foramina open : tibio-tarsus with moderately 

 developed ento- and ectocnemial crests. Fibular ridge well-marked. 

 Tarso-metatarsus grooved anteriorly ; with numerous pneumatic fora- 

 mina immediately above the insertion of the tibialis anticus. Gastro- 

 cnemial ridge moderately well-developed Sula. 



(I. Femur without pneumatic foramina. Tarso-metatarsus slightly grooved 

 anteriorly, with a deep fossa above the insertion of the tibialis anticus, at 

 the bottom of which lie two foramina which pierce the shaft and emerge 

 on either side of the gastrocnemial ridge. Fibidar ridge very strong. 



a' . Tibio-tarsus with strong ecto- and entocnemial crests, the latter reflected 

 outwards. Gastrocnemial ridge very large, its free border expanded 

 into a flattened surface. Tarso-metatarsus comiiaratively slender, 

 length greater than that of the 2nd toe. Patella large, conical. 



Phalacrocorax. 



v. Tibio-tarsus with the free edge of the entocnemial crest looking 

 straight forward, not reflected outwards. Gastrocnemial crest mode- 

 rately well-developed. Tarso-metatarsus short and broad, length less 

 than that of the 2nd toe. Patella flattened, with a groove running 

 obliquely across the middle for the tendon of the ambiens ... Plotus. 



C. Fibula fourth-fifths as long as tibio-tarsus. Femur nearly as long as fibula, 

 very thick relatively to the tibio-tarsus, and highly pneumatic ; with a 

 popliteal fossa containing a pneumatic foramen. Tibio-tarsus non-pneu- 

 matic; cnemial crests feeble; fibular crest feeble. Tarso-metatarsue extremely 

 short, resembling that of the Penguins, the three metatarsals being 

 indicated by grooves ; the length of the tarso-metatarsus one-third greater 

 than the width measured across the trochlese Fregata. 



Phcdacrocorax and Sula have each a free sternal rib attached to 

 the posterior border of the last thoracic vertebra. 



The vertebral column of Pelecanus is peculiar in that, of the 

 thoracic vertebrae, only the 1st is free, the remainder being fused 

 one with another and with the syusacrum. The transverse pro- 

 cesses of the 2nd, '-5rd, and 4th have ankylosed one with anotber, 

 and the whole is fused with the anterior border of the preilium, so 

 that, at first sight, it would appear as though this extended as 



