15 
sacrum, The last pair of ribs, articulated in both species to a sacral vertebra, have heema- 
pophyses which do not reach the sternum. The chief numerical difference in the vertebral 
column is in the excess of caudal vertebre in the Garfowl. The dorsal vertebra have 
the same simple shallow ball-and-socket joint, the ball being anterior in Alca torda, as in 
A. impennis ; and this structure I have also found more feebly developed in the dorsal of 
Uria grylle: in Phaleris both co-adapted surfaces are nearly flat. The main difference 
in the skull is the shortness, greater relative depth, and stronger convex curve of the 
upper contour of the solid prenarial part of the premaxillary : every other better cha- 
racter of affinity is very closely repeated. 
The sternum of Alca torda repeats the characteristics of that of Alea impennis, with 
the exception of a notch on each side of the back part, 1 inch long by 3 lines wide. In 
Alca (Phaleris, Temm.) psittacula, Pallas, the sternum is more dilated posteriorly, and 
the notches are represented by oblong foramina of a wider form, The interorbital part 
of the cranial roof is narrower, and the upper end of the lacrymal projects upward and 
backward as a process. In Uria gryile (Pl. U. fig, 14), besides the posterior notches 
(f) answering to those of Alca torda, there is a small perforation, sometimes two 
(ib. f', f"), on the inner side of each. 
The furcular and scapular arches of Alcea torda closely correspond with those of Alca 
impennis. The coracoid is similarly perforated for a branch of the pectoral artery, 
The humerus closely agrees in shape and proportion ; the difference in the wing-bones, 
in adaptive relation to the power of flight, of Alea torda, begins to manifest itself in the 
antibrachial bones, which are longer and less compressed than in Alca impennis, the ulna 
also having a row of quill-pits or knobs: the bones of the head are shorter relatively to 
the ulna than in Alca impennis. 
A closer resemblance is maintained between Alca torda and A. impennis in the bones 
of the pelvic limb, and is especially seen in the shape and proportions of the rotular 
process, with its pro- and ecto-cnemial ridges, and in the proportions and attachments 
of the fibula, 
The sum of the comparisons of the skeleton of Alca impennis with that in other Auks, 
Phalerins, and Puffins, and also in Guillemots, goes to exemplify the close affinity of the 
Garfowl to those sea-birds, and to indicate that it is a modified apterous member of the 
Alcade. 
The Penguin, similarly apterous or with wings reduced to the function of fins, shows 
its essential distinction from the Garfowl in all the flight-giving parts of the skeleton. 
The number of vertebrze between the skull and sacrum is, indeed, the same ; but only 
eight support moveable ribs, the total number of which is nine pairs, the last pair being 
sacral. The atlantal hypapophysis is produced below into a compressed process; the 
anapophyses of the axis and two following vertebre are mere tuberosities, not elongated 
into processes. ‘lhe pleurapophyses are styliform and produced backward in the third 
to the tenth cervical, thence are shortened to the fourteenth, when the pleurapophysis 
