250 LILLJEBORG ON THE 



of the Basques was, in consequence of these deficiencies, not recognised by G. Cuvier, but 

 taken from the number of the species, and has been quite recently restored to science by 

 Eschricht and Reinhardt. This seems sufficient to show the former state of the study of 

 cetology. 



Balænidæ. 

 Corpus infra antice 



sulcis crebris longitudinalibus f perfecti . . 1. Balænoptera, Jj^icép. 



aratum. j 



Processus coracoideus et aero- \ imperfect! 



mion scapulæ [ vel nuUi . . 2. Megaptera, Gray. 



sulcis carens 3. Balæna, Lin. 



\st Genus. Balænoptera, Lacépede. 

 {Pterobalæna, Eschricht.) 



Eorm of body more or less slender and elongated,' the greatest circumference about or before 

 the middle ; the hind pai't much more slender than the fore part and very compressed near the 

 caudal fin. Head not very large, and tapering forward. Pectoral fin short, with the anterior 

 edge even. Dorsal fin generally rather high and conspicuous, placed far back above the vent. 

 Caudal fin more or less forked in the hinder edge. Eore part with numerous longitudinal 

 furrows beneath, the middle ones being the longest and extending to the middle of the body. 

 Baleen small and short, more or less twisted. 



In the skeleton, the facial part, or the beak of the skull, is rather broad, and seen from the 

 side, but little curved, hence the distance from the nose to the lower jaw is not considerable. 

 Wlien the skull is seen from above, the intermaxillary bones appear much narrower than the superior 

 maxiUaries. Processus coronoideus of the lower jawbones generally rather high and distinct. 

 Cervical vertebrae separate, sometimes one pair united by the processus spinosi. Bodies of the 

 lumbo-sacral vertebræ and the anterior caudal vertebræ larger than in the succeeding genera, 

 and with their lower sides generally carinated in the former vertebræ, although the keel is 

 sometimes slightly, or not at all perceptible in the first and those nearest to it. The processus 

 transversi of these vertebræ are shorter, and the processus obliqui of the anterior caudal vertebræ 

 less separate than in Balæna. The sternum is very variable in its form. The ribs, although 

 sometimes rather large, are generally smaller than in the succeeding genera, which is in accord- 

 ance with the more slender form of the body. The scapula has the coracoid process and acro- 

 mion fully developed and conspicuous, and is comparatively smaller than in Balæna, and of a 

 wider form than that genus, so that its length from the glenoid cavity to the opposite upper 

 edge is considerably less than its width. Its general form seems to correspond in all the 

 known living species. The head of the humerus is more terminal and directed less obliquely 

 than in Balæna, and the lower arm-bones are more elongated. Carpal bones 5, and fingers 4. 



^ The characters based upon the external form of body, the fins, &c., can of course be applied 

 only hypothetically to the subfossil species, -which is only known by a part of the skeleton. 



