/. SIUIiAI.DlU.S. IQ(). 



with the additional two caudal vertebras, the wide luaxillaries, the 

 more elongated metacarpals, and the sliglit differences in tlie form 

 of the cei-vical vertebrue and the ribs, are sufficient to establish a 

 well-marked species ; and, unless it can be identified with any that 

 has been previously described, I would suggest the name of lafi'rostris 

 as an appropriate designation.'' — Flower, P. Z. S. 1864 411-414 



B. T ertcbrce^ii. Thejirst rib douhle-headed. J'J ■ 



7. SIBBALDIUS. 



The pectoral fins moderate. The sectmd cerncal vertebra with a 

 broad elongated lateral process, perforated at the base. The first 

 and second ribs double-headed. Lower jaw compressed, high, flat 

 on the sides, with a conical coronoid process. Yertebrfe 55 or 56 

 Ribs 13 . 13 or 14 . 14. 



Balrenoptera, sp., Gt-ui/. 



Pterobalsena, sp., Esciirtcht, Van Benedon. 

 7 Sibbaldus, arm/, Proc. Zool. 600. 1864, 223; Ann. &• Man. N. H. 

 1864, xiv. .'v')2. 



Sibbaldiiis, Flower, Proc. Zool. Soc. 1864, 392. 

 Pectoral fin one-eighth of the entii-e length ; and the dorsal fin 

 " opposite the opening of the vent," nearly three-fourths of the entire 

 length from the nose. SkuU very broad. Maxillary bones verv 

 broad, graduaUy tapering, with nearly sti-aight outer edges. The 

 intermaxillaries moderate, linear. The frontal bones broad, band- 

 like, with a wide sinuous edge over the orbits. Kasal bones small. 

 The lower jaw slightly arched, compressed, with a conical ramus 

 near the condyle. The lateral process of the second cervical vertebra 

 expanded, with a basal perforation (Rudolphi, Berl. Trans. 1822, 

 t. 1. f. 2). Tympanic bone oblong, ventricose (see Dubar, t. 4. f. l\ 

 Rudolphi, t. 3. f. 6). The lateral processes of the second to the sixtli 

 cervical vertebrae separate, elongate. The arm -bones* strong the 

 forearm-bones nearly double the length of the humerus. The sca- 

 pula broad, with a large, well-develoiied coracoid process in front 

 The hand with four rather short fingers ; the second and third equal 

 and longest : the inner or fourth rather shorter than the first 

 Phaknges 4.5.5. 3. Vertebra? 54. Ribs 13 or 14. The first rib 

 slender, with a process on the side near the condyle, as if the rib 

 was divided into two somewhat similar lobes above (Rudolphi, t 5 

 f. 6). According to Dubar, the first rib is articulated to the first 

 and second dorsnl vertcbra\ 



The under jaw less curved; but the great character is that the 

 front rib is split into two separate parts near the coiidvle, or double- 

 headed as Dubar calls it. The tvmpanic bones are "short, oblono- 

 swollen (figured tn situ in the skull, Rudolphi, /. c. t. 3. f. 6). '" ^q 



" Total nuni])er of vertebra) Jfc»-58. JUbs 14 pairs. Orl)ital i)ro- ^^v 

 cess of frontal bone nearly a^)/oM\ at out(>r end as at the base 

 Xasal bones elongate, narrow, flat, or verv sli-litlv hollowed on the 

 sides of the upper surface, obliquely truncated at" the anterior end 



