227 



the duct of which pMSM through a deep notch at the anterior part of the raprrorbital ridge. 

 1W bate at the tkull is also peculiar for a large and very drrp circular fossa, opening ante- 

 rior to the articular cavity uf the tympanic bone. The number of vertebne between the 

 skull and the iarrum is 20 : the fint Mcral or anchylosed vertebra tupportf the but pair of 

 MMble rib* ; this rib, like the donal ones, hat a double articulation, viz. with the centrum 

 and diapophysis of iu rertebra. It if also articuUted by a bony hirina|Mipliy>in, or itrmal 

 rib, with the (ternum through the medium of the antecedent rib, to the iternal extremity of 

 which it u anchylosed. The sternum u broad, very convex, with a flout keel, entire, and 

 with four nnall rounded notches upon its posterior margin ; at its anterior margin it presents 

 on each side two distinct and remote articular surfaces for the very broad and short cora- 

 coidi ; the anterior of these surfaces consists of a wide groove continued at one end upon a 

 convex surface ; the posterior surface is a deep but narrow notch ; the furrulum is compara- 

 tively slender, but forms a wide arch ; it is articulated to the flattened apex of the sternal 

 keel. Seven pairs of ribs are completed by bony hsemapophyses, and the first five pairs sup- 

 port aiM-hy losed appendages ; these are preceded by a long and slender sty liform rib, reach- 

 ing to, but not articulating with, the sternum. The scapula is long and unusually slender, 

 retaining Us normal form as a pleurapophysu. The deltoid ridge of the humerus is com- 

 pressed and angular ; the sliaft of the humerus is slightly compressed, and becomes trihedral 

 towards its distal end, a ridge extending to the outer condyle, above which a short, well- 

 marked process stands oat. There is a small pneumatic foramen at the base of the deltoid 

 process. The shaft of the ulna presents an oval transverse section and two rows of rough 

 spots, indicating the attachment of the great quill-feathers ; it has no pneumatic foramen ; 

 the medullary arterial canal runs distad. The shaft of the long and slender radius is trihe- 

 dral ; it is also a marrow-bone. The metacarpus consists as usual of three metacarpal 

 MM, anchylosed together, and to a carpal bone, answering to the os magnum at the proxi- 

 mal end. The largest metacarpal is that of the ' medius ' digit ; the slender one of equal 

 length ia that of the ' annularis ' or fourth digit ; the metacarpus of the index is a short rudi- 

 ment. The principal metacarpal is deeply grooved for the passage of an extensor tendon. 

 The bones of the leg are comparatively short : the femur is but a fourth part the length of 

 the humerus and presents a large and distinct pit for the ligamentum teres, on the upper part 

 of the head : the trochanter does not rise so high as this part. The tibia is more than twice 

 the length of the femur ; it is chiefly remarkable for the great development of the pro- 

 cnemial and ectocnemial ridges and of their common base. The tendinous canal at the fore- 

 part of the distal end is crossed by an osseous bridge. The metatarsus has a four-sided 

 shaft, deeply grooved, but not perforated, at the back part of its proximal end : it is per- 

 forated above the interspace between the middle and internal trochlea. There are 6 free 

 caudal vertebrae. 



Purchased. 

 1 190. The skull of an Albatroe (Diomedaa erulaiu). I Interim. 



\ 191. The skull of an Albatros (Diomedaa exuUau). Htmteria*. 



2o2 



