FINS OF ELASMOBRANCHS. 447 
small pieces of cartilage again fringes the preaxial edge of the series formed by the 
coalesced preaxial radials. It may be, however, that the coalesced piece (cr) may be 
more properly termed the propterygium. The two next radials also coalesce proxi- 
mally to form a subquadrate cartilage which joins the preaxial part of the distal end of 
the elongated more preaxial cartilage. 
The accession of cartilages to the normal preaxial edge of this fin-skeleton has been 
so great that I should be tempted to consider these coalesced cartilages as the propte- 
rygium, and the propterygium as the mesopterygium, but for the examples of Chilo- 
scyllium, Chimera, and Callorhynchus, and but for the close resemblance of this small 
proximal piece (p') to the small propterygial cartilage of Notidanus. 
The radials generally are much segmented, and extend distad much further on the 
preaxial than they do on the postaxial side of the limb. 
Not one (as in Chiloscyllium), but five radials are crowded together, and interposed 
between the meta- and propterygium; and of these the median one extends slightly 
further proximad than do the others, which are so crowded and superimposed that they 
cannet be distinguished till the parts are more or less separated. Of the radials 
attached to the propterygium, the first two coalesce proximally, the five others, more 
postaxial, are single. All the radials are much segmented, and mostly expand somewhat 
distally, while none appear to bifurcate. The skeleton of the limb projects distad most 
towards its preaxial margin. 
CHILOSCYLLIUM OCELLATUM. 
Dorsau Fin (Plate LX XVI. fig. 3). 
This small fin has a skeleton which consists of three superimposed series of conjoined 
cartilages, as in Mustelus antarcticus—a series of elongated median cartilages, a series 
of short distal, and another series of short basal cartilages. The whole structure is 
separated from the subjacent axial skeleton by a side interval occupied by strong fibrous 
membrane. 
The basal cartilages are thirteen in number, and are all nearly equally short, though 
those towards the postaxial end are somewhat less so. There is no sign of coalescence 
between even any two of them. 
The median cartilages are also thirteen in number. The most preaxial pair are very 
short indeed; but all the others are much elongated, the sixth being most so, and the 
rest slightly decreasing in length postaxiad. 
The distal cartilages are but eleven, there being none to the first two median carti- 
lages. The second of these eleven is the longest of all, and then the first and third. 
They then decrease in length to the eighth and ninth, while the tenth and eleventh 
are slightly longer. The four shortest are shorter than any of the basal cartilages, 
while the three most preaxiad are longer than any of the basal cartilages. The 
VOL. X.—PART X. No. 2.—February 1st, 1879. 3P 
