12 



W. LILLJEBORG, 



the tipper end cloven or biceps and the lower largely emarginated. Number 

 of vertebrae probably about GO, all the cervical vertebrae separate. The atlas 

 has the lateral processes above the middle and of a conical form. Only the 

 epistrophaeus has annular side-processes. Number of ribs about 14 pairs. 



Of this genus there is as yet hut one species with which we are acquain- 

 ted, viz. the great Ostende- or Giant- Whale Flowerius gigas (Eschricht), 

 Sibbaldius borealis Gray. By Gray it has been ranged in the genus Sib-, 

 baldius, hut it differs so much both in exterior and interior characteristics 

 from the Sibbaldius laticeps Gray and Sibbaldius Schlegelii FLOWER, that it 

 ought in our opinion to he considered as the type of a separate genus. Its 

 dorsal fin differs both in situation and form, and the lateral processes of 

 its cervical vertebrae are different, &c. 



4. Genus SIBBALDIUS, J. Gray. 



Form of body slender and elongated, with small pectoral fins, and 

 dorsal fin of middle dimensions, and situated just behind the commencement 

 of the posterior third of the body's length. Processus coracoideus and acromion 

 strongly developed, processus coronoideus high. First pair of ribs with upper 

 end cloven or biceps and the lower end not holloived out. Number of verte- 

 brae 55 — 58. Lateral processes of atlas compressed, and situated in about 

 the middle of the sides. The old individuals have the lateral processes on the 

 epistrophaeus and nearest adjacent vertebrae annular. Number of ribs 13 — 

 14 pairs. 



According to Flower and Gray we know with certainty two species 

 of this genus, and tere is a third which according to Gray may perhaps 

 be considered as belonging to it. The first, S. laticeps Gray, is from the 

 North-sea and North Icy Ocean, the second, S. Schlegelii Flower is from 

 the seas about Java; and the 3 rd , S. antarcticus BURMEISTER, of which we 

 know only the bladebone, and which therefore cannot with certainty be 

 ranged in this genus, is from the seas about the south-eastern coast of 

 South America, in the neighbourhood of Buenos-Ayres. 



5. Genus ESCHRICHTIUS, J. Gray, 



including the species E. rohistus (Lilljeborg) or Balaenoptera robusta 

 Lilljeborg, of which more hereafter. 



