444 PROF. ST. GEORGE MIVART ON THE 
Tue Ventral Fin (Plate LXXYV. fig. 4). 
The ventral-fin skeleton consists of a closely set series of rays, nineteen being attached 
to an elongate basal cartilage (4), and the remaining four (mostly much shorter) more 
preaxial rays being attached to the pelvic cartilage (p). Very short, more distally 
situated cartilages are attached to and between the distal ends of the more proximal 
rays; and there is a trace of yet another, third, or most distal series, in the form of five 
minute cartilages, situated, again, between the more preaxial (excepting the first) of 
the small cartilages just described. The general resemblance of this structure to that 
of the dorsal fin is very noteworthy. 
Tue Ana Fin (Plate LXXYV. fig. 5). 
Here we have again a closely set longitudinal series of eighteen cartilaginous rays, 
or radials, attached to a more solid basal structure. The seven more preaxial rays are 
much larger than the succeeding ones; always segmented, they are somewhat irregularly 
so. The succeeding more slender rays are not all segmented. The nine most postaxial 
rays are attached to one large and long continuous basal cartilage. The next six have 
a solid cartilaginous support for each pair. The ray next preaxiad has a cartilaginous 
support to itself, preaxial to which the basal cartilage seems irregularly segmented, 
longitudinally as well as vertically. The base of this fin has every appearance of having 
been formed by the coalescence of the basal parts of its constituent radials. 
Tue Pecrorau Fin (Plate LX XV. fig. 3). 
The propertion borne by the basal cartilages, as a whole, to the rays is very large in 
the pectoral of this species. 
The metapterygium (c) is very elongated, very narrow, and once segmented towards its 
proximal end. It expands greatly distad. It supports fifteen radials. 
The mesopterygium (6) is also very large, triangular, with its shortest side proximad. 
It supports ten radials, including the most preaxial ones, as it extends to the preaxial 
margin of the limb; on which account I am disposed to regard this cartilage as consist- 
ing of mesopterygium, with the distal part of a segmented propterygium confluent with 
it. Indeed I know of no definition applicable to these cartilages, save what can be 
drawn from their position with respect to the limb-axis. 
The propterygium (a)—or, if the view above stated is correct, the proximal part of 
the propterygium—is exceedingly small, broader than long, and is entirely excluded 
from the radials by the extension preaxiad of the mesopterygium to the preaxial 
margin of the limb. 
I find the first (most preaxiad) radial to be, in the specimen depicted by me, slightly 
the broadest at its base, and to consist of four segments; but the segments of the 
radials generally are somewhat irregular. Those attached to the mesopterygium are 
