ADDITIONS AND COKEECTIONS. 381 



more than 15. The first rib in both the Hull and Utrecht specimens 

 differs from P. antiquorum in wanting a well-developed capitular 

 process. In the Ftrecht specimen this process is present in the 

 second, third, and fourth ribs — ^longest in the third. In the HuU 

 specimen it is found in the second, third, fourth, fifth, and sixth 

 ribs, being longest in the third and fourth. In P. antiquorum it is 

 usually longest in the second, and obsolete in the fourth. 



The phalanges of the digits in both skeletons are articulated arti- 

 ficially, and yet they correspond exactly in number and arrangement, 

 except that the Hull specimen has an additional bone on digit III. 

 The numbers are, II. 4; III. 5 (Utrecht), 6 (HuU) ; IV. 5 ; V. 3,— 

 an arrangement somewhat different from .that of P. antiquorum. One 

 of the most striking and characteristic differences in this part of the 

 skeleton is the greater length of the metacarpal bones and phalanges, 

 which in both the Hull and Utrecht specimens, not only relatively 

 but even actually, exceed those of the fuU-grown P. antiquorum of 

 70 feet in length. 



The baleen, which is not preserved in the Utrecht specimen, in 

 the Hull specimen is in excellent condition, and shows a striking 

 difference from that of the common Fin- Whale in being of a uniform 

 deep black, instead of dark oUve-brown or horn-colour variegated 

 towards the ends of the series with patches and stripes of a lighter 

 colour. 



After description of Sibbaldius Schlegelii, (at page 186) add : — 



Sibhaldius ? antarcticus. 



Sibbaldius antarcticus, Burmeister, Proe. Zool. Soc. 1865. 



Inhab. coast of Buenos Ayres, near the mouth of the river Salado, 

 (Bladebone in Mus. Buenos Ayres.) 



The bladebone (the only portion of the skeleton saved) flat, nearly 

 one-third of a circle, half as high as broad ; the outer margin is 

 regularly curved, with an indication of an obtuse angle on the hinder 

 part of the circumference ; towards the glenoid cavity it becomes 

 much thicker, and has here the thickness of the diameter of the 

 glenoid cavity. The outer surface is somewhat excavated, with the 

 indication of an obtuse radial crest on the beginning of the hinder 

 half. The inner surface is flatter, and has five large and three short, 

 obtuse, radial, elevated Hnes. The front margin is thin, with the 

 indication of an obtuse angle in the upper half, and under that 

 angle are two descending small spines. The hinder margin is some- 

 what curved to the interior, but more straight in the middle of its 

 course. 



The acromion is a very large, compressed process, which is some- 

 what broad and rounded at the end, and with two obtuse humps on 

 the under margin near to the base. The upper margin is very short, 

 and continued on the outside of the bladebone as a sharp, prominent 

 crest. The coracoid process is only half the size of the former, and 

 obKquely truncated at the end. The glenoid cavity is a broad ellipse. 



