7. SIBBALBIirS. 175 



transverse process of the vertebra. The &8t pair of ribs have double 

 heads ; but the anterior head oa both sides is very incompletely deve- 

 loped, and on the right side completely detached from the remainder 

 of the bone ; it has a pointed end below, merely applied to the main 

 part of the rib ; so that if it had been lost in maceration, this rib 

 might have been supposed to be simple. On the left side it is anchy- 

 losed, but very slender. It would be interesting to ascertain, by the 

 examination of younger specimens, whether this anterior head has 

 always a separate centre of ossification, as it is not improbable that 

 this singular double-headed bone is in reality formed by the coales- 

 cence of two originally distinct ribs. The second, third, and fourth 

 ribs have small capitular processes. The stylo-hyals are very flat, 

 but not so broad proportionately as in the Java "Whale, being 11" 

 long and 3^" in greatest width. The bones of the fore limbs present 

 the same general characters and proportions as in the Leyden spe- 

 cimen from the Zuyder Zee. The sternum is absent. 



" This specimen has been previously mentioned in this paper as 

 an example of Sibbaldhis laticeps. Gray, presenting some interesting 

 individual deviations from that at Leyden, referable to the develop- 

 ment of the two skeletons not having proceeded pari passu in all 

 parts of the system."— i^'Zower, P. Z. S. 1864, 417. 



* * Dorsal Jm very small, far behind, and placed on a thick prominence. 

 Mibs M . 14 ; Jirst short, sternal end very broad and deeply notched. 

 Sternum with a broad short hinder lobe. Os hyoides transverse ; sides 

 slender ; hinder edge cut out in the middle, 



2. Sibbaldius borealis. The Flat-hack. 



Sibbaldus borealis, Gray, P. 'A. 8. 1864, 223; Ann. <&• Mag. N. H. 



1864, xiv. 352. 

 Baleine d'Ostende, Van Breda, en letter bock, 1827, 341 ; Dubar, Os- 



t6ographie, BruxeUes, 8vo, 1828, t. 1-10 ; Bernaert, " Notice sur la 



Baleine echou^e pres dOstende," Paris, 1829. 

 Baleinoptere d'Ostende, Van der Linden, 1828, BruxeUes, 8yo. 

 The Ostend Whale, Guide to the Exhibition at Charing Cross, with 



dramngs by Scharff. 

 Great Northern Rorqual, " R. borealis, Lesson" Jardine, Nat. lab. 



125. t. 5 {from Scharf). 

 Balsena borealis (part.), Fischer, Syn. 524 {from Dubar). 

 Balsenoptera Rorqual, Dewhurst, Loudon Mag. N. H. 1832, v. 214. 

 Balaenoptera gigas, Eschr. Sf Reinh. Nat. Bidrag, af Groenland, 1857 ; 



Lilljeborg, I. c. 56, 57 ; Mahngren, Arch. Naturg. 1864, 97. 

 Pterobalsena Boops' (part.), Eschr. K. Dansk. Vidensk. 1849, 134. 

 Pterobalaena gigas. Van Beneden, Mem. Acad. Roy. Sci. Bnuc. 1861, 



xxxii. 37, 463 (not characterized). 

 Female : — 

 Balsenoptera Boops, Yarrell, Proc. Zool. Soc. 1840, 11. 

 Balaenoptera tenuirostris, Sweeting, Mag. Nat. Hist. 1840, iv. 342. 



Inhab. North Sea. 



" A whale was observed floating dead in the North Sea between 

 Belgium and England," and -towed into the harbour of Ostend on 

 the 4th of November 1827. The skeleton was exhibited at Charing 

 Cross, and is now, I beheve, in the United States. 



