THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIO. 257 
assigned to it hy Gasco, he expresses the opinion that there may originally have 
been 14 pairs. 
In the majority of specimens the first rib is single-headed, but in the Guetaria 
(Spain) skeleton, that of the right side shows a small secondary process adjacent 
to the proximal end. The bifurcation is also found in the San Sebastian skeleton 
of 1854. Gasco’s description of the first pair of ribs in this specimen is as follows: 
“No doubt the first pair of ribs of the young whale of San Sebastian, placed 
opposite the corresponding parts of the Taranto whale, exhibit certain singular 
differences, which though they do not surprise us at present, led J. E. Gray to 
ereate the genus Hunterius, a genus which no one now accepts. The superior or 
vertebral extremity of the first pair of ribs is bifureated. In the right one the 
bifurcation extends 55 mm., but in the left does not surpass 15 mm. In the left, 
the part of the rib which thus separates, 15 mm. long, terminates acutely and may 
be compared to a little horn, which has the apex distant scarcely 2 em. from the 
internal border of the rest of the rib, and about 7 cm. from its superior extremity. 
Its circumference is 45 mm., and at the apex, 25 mm. On the other hand, on the 
right the portion of the rib which is separate is 55 mm. long. It is somewhat 
thicker, the termination obtuse, and it is distant its whole length only 3 or 4 mm. 
from the inner margin of the rest of the rib. So it may even be suspected that in 
the progress of time this portion might be completely fused with the rest of the 
rib. Its apex is distant from the superior extremity of the rib only 2 em. Its 
circumference at the base is 8 cm., and 9 cm. near the apex. All these relative 
differences in the degree of bifureation in the same individual indicate clearly how 
little of importance there is in the separation of a portion of the rib.” ! 
The distal ends of the two ribs constituting the first pair are commonly unequal 
in breadth. In the different specimens the measurements are as follows: 
BALAINA GLACIALIS BONNATERRE. EUROPEAN AND AMERICAN. BREADTH OF FIRST RIB. 
Locality. Left. Right, 
in. in, 
(Cmca, Seis ane aawes caopad aco see 7.0 6.2 
Wparamton littallivencts wera ica sysla sree. cele. 3.9 aoe 
‘Seay SEDEGUENN, SOE Neoscog bao ato mode 6.6 5.9 
Mone wlclewNe Men (EveldliColy Mus) eee 8.0 8.75 
Cape Lookout, N. C. (Raleigh Mus.)......| 6.5 6.75 
iWoue lids Ns ve (Aimer, Mush). <2)... 05.6. 5-75 6.5 
Amagansett, N. Y. (Natl. Mus.)........... Bere 4.5 
(Cingdlestion, S35 (Crsscoscahobo noaoosee sons 4.5 6.0 
(COIs: vert INNGir lGisey “ob aronodo neaseuo cor Bn25 3.85 
The length of the first rib in a straight line is as follows: 
‘Annal. Mus. Civic. Genova, 14, 1879, pp. 606, 607. * Type of B. cisarctica. 
