448 PROF. ST. GEORGE MIVART ON THE 
apices of the two most preaxial distal cartilages are pointed ; but the rest are truncated 
apically. 
Tuer VenTRAL Fin (Plate LX XVI. fig. 5). 
Here we have a very simple skeleton, consisting of sixteen radials, whereof two are 
attached to the pelvic cartilage (p), and the rest to an antero-posterior basal cartilage (2) 
of nearly equal width throughout. The fourth radial is the longest; and thence they 
decrease gradually in length in each direction. 
Distal cartilages are attached, one to the apex of each elongated cartilage, from the 
second to the eighth inclusive. That attached to the fourth long cartilage is the 
longest ; and thence they rapidly diminish, both preaxiad and postaxiad. 
Tue Pecrorau Fin (Plate LX XVI. fig. 4). 
In this fin there are but two basal cartilages (m and p), separated by a wide mem- 
branous interval. They are both long cartilages, and of subequal length. 
The metapterygium is undoubtedly represented by the more postaxial of these two 
cartilages; it supports distally six radials. 
The mesopterygium may possibly be represented, as well as the propterygium, by the 
more preaxial basal cartilage; but I am inclined to regard it as absent, since (as before 
said) it is hard to find any definition of a “ mesopterygium ” save that of ‘a basal carti- 
lage occupying the middle region of a limb-axis.” This absence is, moreover, the less 
surprising when we consider the conditions which exist in Chimera and Callorhynchus. 
The propterygium is represented by the preaxial basal cartilage, which is as elon- 
gated and large as the mesopterygium. It has a strongly concave mediad margin, and 
expands distally to give attachment to nine radials. The most preaxiad radial creeps 
up, as it were, along the preaxial margin of the propterygium to about its middle, thus 
presenting a much less development of what we found in Ginglymostoma. It consists 
of three segments. In the radials attached to the propterygium the middle segment is 
the broadest, and the distal segments are so applied to their supporting cartilages that 
the adjacent sides of the distal ends of these (from the fourth to the ninth) support a 
distal cartilage between them. 
One radial has its proximal apex placed, not against, but between the pro- and 
metapterygiun. Its distal cartilage is medianly divided, so that there are two little 
terminal cartilages placed side by side. The same is the case in the terminations of the 
three next more postaxial rays. The last three (most postaxial) rays do not show any 
distinct signs of segmentation in my specimen. 
It is the proximal part of the limb-skeleton which projects furthest distad. 
