456 PROF. ST. GEORGE MIVART ON THE 
Seconp Dorsau Fin (Plate LX-XIX. fig. 2). 
The skeleton of the second dorsal fin is of the simplest possible character, consisting, 
as it does, of a longitudinal series of subvertically placed, not quite contiguous, carti- 
laginous radial pieces, forty-one in number. ‘They increase very slowly in length post- 
axiad from the first to about the eighth, remain much the same to the tenth, then rapidly 
decrease in length to the fifteenth, then very slowly to the end. This skeleton is nowhere 
in contact with the axial skeleton, but is separated from it by a wide tract of fibrous 
tissue, which shows very plainly the lines of attachment of the intermuscular septa 
sloping dorsad and preaxiad. The number of these does not at all correspond with 
that of the fin-radials. 
Tur VENTRAL Fin (Plate LX XIX. fig. 4). 
The cartilaginous skeleton of this fin is very unlike that of other Elasmobranchs’ ven- 
trals, and recalls to mind the skeleton of their pectoral fins. Thus, ¢. g., ifin the skeleton 
of the pectoral fin of Acanthias blainvillii the protruding preaxiad radials were shortened 
and the basals fused and contracted, we should have very nearly the condition we find 
in the ventral of Callorhynchus. We have, indeed, already in Scymnus lichia an example 
of a single cartilage taking the place of the pro-, meso-, and metapterygium. 
In the ventral of Callorhynchus we have one large basal cartilage, the proximal 
margin of which exhibits an articular concavity to fit on to the articular surface 
(Plate LX XIX. fig. 5) of the pelvic cartilage. 
This basal cartilage must answer to the pro-, meso-, and metapterygium of an Elasmo- 
branch pectoral, and is deepest on the postaxial or metapterygial side. Its distal curved 
margin is even and continuous, except a preaxial continuity with the radials, like that 
foundin Chimera!. Here, however, the process is less distinctly marked. These radials, 
at first very short, increase in length postaxiad to about the eleventh, and decrease from 
about the fourteenth. At the apex of each is a small cartilaginous segment, longest in 
the more preaxial radials, 7. ¢. postaxiad of the second radial. The first radial bears 
two small cartilages, side by side, at its distal end. The bases of the twelfth, thir- 
teenth, fourteenth, and fifteenth radials haye combined to form a small plate interposed 
between their distinct proximal ends and the distal margin of the basal cartilage. 
The skeleton of the fin projects distad most a little protaxial to its antero-posterior 
middle, about opposite the bottom of the concavity of the distal margin of the fin 
as formed by its fin-rays. 
Tue Petvis (Plate LX XIX. fig. 5). 
The pelvic cartilage is very remarkable, and far more like the pelvis of a Batrachian 
than is any other fish-pelvis known to me. The right and left halves are separate. 
Each consists of a solid mass of cartilage (ip), which may be called éschio-pubic, from 
Gegenbaur’s ‘ Das Skelet der Gliedmassen der Wirbelthiere im Allgemeinen,’ plate xvi. fig, 22, R. 
