320 DR. J. E. GRAY ON A NEW BRITISH PORPOISE. [Mar. 28> 
which are more crowded near the upper end of the fin. Dorsal 
jin in the middle of the back. 
2, PHOCZNA TUBERCULIFERA, Sp. nov. 
ITab. Mouth of the Thames, Margate. 
c. Back in front of the dorsal fin with a single series, and upper 
surface of the dorsal fin with three series, of square-based com- 
pressed tubercles or spines. Dorsal fin behind the middle of 
the back. 
3. PHoc#NA SPINIPINNIS, Burmeister, P. Z.S. 1865, p. 228. 
Hab. Rio de la Plata. 
The new species may be described as follows :— 
The specimen was 52 inches, measured along the side from the 
end of the nose to the notch in the middle of the tail. The front 
edge of the dorsal fin is 23 inches from the tip of the nose, measured 
over the arch of the back; the hinder edge of the dorsal fin, mea- 
sured in the same manner, is 22 inches from the notch in the tail. 
The front edge of the base of the pectoral fin is 9 inches from the 
end of the nose; and the fin itself is 9 inches long, measured along 
its front margin. The tail is 13 inches wide, measured across the 
hinder edges ; the lobes are rounded, and rather overlap each other 
at the central notch. 
The hinder part of the back, the whole of the dorsal fin, and the 
upper and lower surfaces of the pectoral and caudal fins are black ; 
the head, the lower lip, the front part of the back, and the sides to 
the base of the pectoral fins are greyish black; the upper parts of 
the sides of the body behind the pectoral fins are grey, more or less 
mottled with a darker shade; the chin, throat, chest, belly, and 
under parts of the body white. The upper and lower jaws are of 
the same length. The upper lip covers the edge of the lower one, 
the covered part being pale-coloured, flattened, and gradually shelv- 
ing in towards the upper margin. There are two minute pits (which 
may have been the places from which whiskers arose) in the upper 
part of the upper lip, situated about where the depression is placed 
that separates the beak from the head in those genera which have 
the beak marked. 
The dorsal fin is scarcely falcate, with a rather broad, rounded 
upper margin, which is armed with a single series of distinct com- 
pressed tubercles ; the tubercles have an oblong base, with a slightly 
raised conical centre, and the surface is covered with irregular radia- 
ting wrinkles. Those on the front part of the edge are largest, and 
separate from one another ; they diminish in size and become crowded 
near the hinder upper part of the fin, forming a ridge, which is hard 
and serrated to the touch. 
The skull is much like that of Phccena communis in size, general 
form, and in the number, disposition, form, and size of the teeth; but 
