240 THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 
The phalanges on digits 4 and 5 cannot, of course, be estimated in the same 
way, as they are not indicated on the posterior margin of the fin. 
STERNUM. 
The sternum has not been preserved in the American skeletons with which I 
am familiar. Fischer (44) has figured the sternum of a specimen from the Antilles, 
which should represent Cope’s J. bellicosa, and Malm (66, pl. 1, fig. 4b) has also 
given a figure of a partially incomplete sternum from St. Bartholomew Island. 
These, with the sterna of two European specimens, are represented in the out- 
lines (text figs. 79 to 83) on p. 239. They show that there is no essential differ- 
ence in the pattern of the sternum in the American and European Humpbacks. 
From a systematic point of view the sternum is of little importance, on account of 
the large amount of individual variation to which it is subject. 
RIBS. 
The first rib in Megaptera is broad at the distal end. In the type of I. 
bellicosa it is cut off square (pl. 35, fig. 2), but in the Tay River whale, according 
to Struthers’s description and figure, the distal end is emarginated, more strongly 
on the right side than on the left, forming an anterior and posterior angle. 
The second rib in JZ, delicosa has an oblong prolongation at the proximal end, 
with parallel margins, from the head to the angle. The second rib in the series of 
ribs from St. Bartholomew Island figured by Malm (66, pl. 1, fig. 4c) is club-like at 
the proximal end, without distinct processes, while the second rib in the Tay River 
whale “has a prominent tubercle, the end sloping obliquely downward and inward, 
giving a broad triangular beak.” This is seen in the third rib of the type of JZ. 
bellicosa, but not in the second. In the Humpback described by Van Beneden and 
Gervais “the third, especially, and the fourth differ from the others by possessing a 
distinct head ” (8). 
It will be seen that no two skeletons agree in the shape of the ribs, and these 
parts therefore do not aid in the discrimination of species. 
SUMMARY. 
From the foregoing presentation of the recorded data relative to the external 
and osteological characters of the Humpbacks of the coast of Europe, Green- 
land, and the North American mainland, the following condensed statement may 
be drawn up: 
1. The average and maximum lengths for the Humpbacks taken at the Finmark 
whaling stations, according to Cocks’s measurements, are larger than the measure- 
ments of those taken at Newfoundland. On the other hand, Humpbacks from 
Bermuda and Greenland are cited as larger than the Finmark specimens. 
2. The Humpbacks of both sides of the Atlantic have the same two colors— 
