I / () BAL^NOPTERID.li. 



This specimen was 102 feet long, the lower jaw 21| feet long, 

 and the fins 13| feet long. Vertebrae 54. Ribs 14 . 14. The atlas 

 {Duhar, t. 6. f. 1): the second cervical vertebra with large lateral 

 processes, pierced with a large hole ; the third, fourth, and fifth 

 with two lateral processes on each side, which are not formed into 

 a complete ling as in the second ; the fifth oft'ers a rudiment of a 

 spinal apophysis. The first rib double-headed, articidated to the 

 th'st and second dorsal vertebrie. IJones of the ears {Dulxir, t. 5. f . 1 ) ; 

 OS hyoides (t. 5. f. 2); breast-bone (t. 0. f. 4) not pierced, short 

 and broad, with a broad hinder portion. The vertebral column '61 . 

 Dubar's figures rejiresent the second, third, and fourtli cervical ver- 

 tebra; as with a ring, and the fifth, sixth, and seventh with defiexed 

 upper and straight lower sei)arate lateral processes. Eibs, first (t. 8. 

 f. 1) with two heads, very broad at lower end; second (f. 2) with 

 rather elongate internal process ; fourteenth (f. 3) (juite simple. 

 Pelvic bones (t. 9. f. 1, 2). Shoiddcr-blade short and very broad 

 on the external edge, with a large lobe for the ridge (t. 10). Pectoral 

 fin and bones (t. 11). Pingers four ; the second and third nearly of 

 equal length, and longest ; the fourth or outer shorter, longer than 

 the first or inner. 



¥\s. 39. 



First rib of Sibhaldius borealis. (From Dubar.) 



The upper jaw narrower and shorter than the lower, so as to be 

 embraced by the lower ; a tuft of horny round filaments or long hairs, 

 united at their roots by a common membrane and divided at the end 

 into small points, at the tip of the snout. Eyes rather high and 

 very near the angle of the mouth. Ear-hole near the eye, but a little 

 further back. Hinder part of the back keeled. Dorsal fin rather 

 less than three-fourths of the entire length from the end of the nose, 

 exactly opposite the vent. Skin polished, black above, white beneath. 

 Length (entire) 25 metres, of mouth 4-8, to pectoral 6'i), to navel 

 13-7, to front of vagina 18*1, to front of vent 18'1. Length of pec- 

 toral fin 3-1, width of pectoral 0-65. The atlas transverse. The 

 lateral processes thick, elongated, rather above the middle of the 

 side {Duhar, t. 6. f. 1). The os hyoides broad in the middle and 

 gradually tapering at each end, and with a deep notch in the middle 

 of the hinder edge (Dubar) (Scharff^s Jh/mr). Tym])anic bone ob- 

 long, very imperfectly figured as the o,? <fn rorlur (t. 5. f. 1). The 



