216 DR. J. E. GRAY ON BRITISH CETACEA. [May 24, 
that the upper margin is narrower than the lower. In the genus 
Balenoptera it is nearly in the centre of the base. 
The genera Megaptera and Rorqualus have separate, short upper 
and lower lateral processes, which are rather dilated and truncated 
at the end, having an interrupted circular perforation between their 
inner bases. It has been suggested that, in the latter genus at 
least, the separated processes may be only the imperfectly developed 
state of the broad lateral process of the genus Physalus, the end 
that is wanting in the skeleton probably existing in the living animal 
in the state of cartilage. But if this should be the case (which I 
much doubt), the form of the margin of the perforation and the per- 
foration itself must undergo great change during the ossification 
of the end of the process for there to be any resemblance between 
the lateral processes of these genera and that of the genus Physalus. 
From what I have observed, I believe that no such change does 
take place, and that the form of the processes and the situation of 
the perforations afford good characters for the separation of the spe- 
cies into groups and the species from each other. 
* The upper and lower lateral processes of the third, fourth, fifth, 
and sixth cervical vertebre elongate, united, forming a ring ; 
the body of the cervical vertebra oblong, transverse, much wider 
than high ; the upper and lower edge nearly straight ; the la- 
teral process of the second cervical elongated. 
PuysaLus ANTIQUORUM. The Razorback. (Figs. 9,10,11,12.) 
Balena maximus borealis, Knox, Cat. Whales. 
Great Northern Rorqual (Knox), Jardine, Nat. Lib. t. 6 (skeleton). 
Physalus antiquorum, Gray, P. Z. 8. 1847, 96; Cat. Cetac. 38 ; 
Heddle, P. Z.S. 1855, 195, fig. verteb. bad. 
Rorqual de la Méditerranée, Cuvier, Oss. Foss. v. 370, t. 26. f. 5. 
Balena antiquorum, Fischer, Syn. 525 (from Cuvier). 
Balenoptera antiquorum, Gray, Zool. E. & T. 50. 
Balena physalus, Turton, B. F. 15; Jenyns, Man. 47; Nilsson, 
Scan. Fauna, 636. ; 
Balenoptera boops (part), Fleming, B. A. 31; Jenyns, Man. 47. 
Balena musculus, Turton, B. F. 16; Jenyns, Man. 47. 
Balenoptera musculus, Flem. Brit. Anim. 30. 
Balenoptera acuto-rostrata, Scoresby, Arct. Reg. i. 485, t. 13. 
F.2: 
Balenoptera boops, Bell, B. Quad. 520, f. 1. 
Bualenoptera physalus, Schlegel, de Dieren, 101, t. 20. 
Fin Whale, Neil, Wern. Mem. i. 201. 
Balena physalus, O. Fab. F. G. 35. 
Physalus vulgaris, Fleming, B. A. 32. 
Balenoptera gibbar, Scoresby, Arctic Reg. 1. 478. 
Pterobalena communis, Eschricht, Van Beneden, Bull. Acad. 
Brux. ser. 1, 1857, 1.390; Nouv. Mém. Acad. Brux. xxxii. (1861) 37. 
Hab. North Sea; North Berwick, 1831 (Dr. Knox) ; skeleton 
