1864. | DR. J. E. GRAY ON BRITISH CETACEA. 223 
a broad elongated process, perforated at the base. The front ribs 
double-headed. 
Balenoptera, sp., Gray. 
Pterobalena, sp., Eschricht, Van Beneden. 
Pectoral fin one-eighth the entire length; and the dorsal fin, 
“opposite the opening of the vent;’’ nearly three-fourths the entire 
length from the nose. Skull very broad. Maxillary bones very 
broad, gradually tapering, with nearly straight outer edges. The 
intermaxillaries moderate, linear. The frontal bones broad, band- 
like, with a wide sinuous edge over the orbits. Nasal bones small. 
The lower jaw slightly arched, compressed, with a conical ramus 
near the condyle. The lateral process of the second cervical verte- 
bra expanded, with a basal perforation (Rudolphi, Berl. Trans. 1822, 
t.1.f.2). Tympanic bone oblong, ventricose (see Dubar, t. 4. f. 1; 
Rudolphi, t. 3. f. 6). The lateral processes of the second to the sixth 
cervical vertebrae separate, elongate. The scapula broad, with a 
large, well-developed 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. Vertebree fifty-four. 
Ribs thirteen or fourteen. The first rib slender, with a process on 
the side near the condyle, as if the rib was divided into two some- 
what similar lobes above (Rudolphi, t. 5. f. 6). According to Dubar, 
the first rib is articulated to the first and second dorsal vertebra. 
The under jaw less curved ; but the great character is that the 
front rib is split into two separate parts near the condyle, or double- 
headed, as Dubar calls it. The tympanic bones are short, oblong, 
swollen (figured én situ in the skull, Rudolphi, J. ¢. t. 3. f. 6). 
SipBaLpus LaTicers. (Figs. 16, 17.) 
Ribs 13/13. 
Balena rostrata, Rudolphi, Berl. Abhand. 1820, t.1 (not Hunter). 
Rorqual du Nord, Cuvier, Oss. Foss. v. 564, t. 26. f. 6 (cop. from 
Rudolphi). 
Balenoptera laticeps, Gray, Zool. E. & T., from Rudolphi. 
Balena borealis, Fischer, Syn. 524, from Cuvier. 
Hab. North Sea; Holstein, 1819 (Rudolphi) ; skeleton in Mus. 
Berlin, 31 feet long. Zuyderzee, 1816, skeleton in Mus. Leyden. 
There is also the first rib of a whale of this genus in the Museum 
of the College of Surgeons, which seems to indicate a fourth species. 
The origin of the specimen is unknown. 
M. Van Beneden, who regarded this as the young of the follow- 
ing, observes that the skeleton in the Berlin Museum from Holstein 
is not quite adult; and also states that there is a skeleton, not quite 
adult, in the Leyden Museum from the Zuyderzee. 
SIBBALDUS BOREALIS. (Fig. 18.) 
Ribs 14/14. 
Baleine d’ Ostende, Van Breda, 1827, 341; Dubar, Ostéographie, 
Bruxelles, 8vo, 1828, t. 1-10. 
