FINS OF ELASMOBEANCHS. 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 (er) 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, Chim(era, and Ccdlorhynchus, 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 

 cannot 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. 

 Dorsal Fin (Plate LXXVI. 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 hasal 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 caiiilages 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. _ 8 p 



