446 PROF. ST. GEOEGE MIVAET ON THE 



GINGLYMOSTOMA CIRRATUM. 

 Dorsal Fin (Plate LXXVI. fig. 2). 



This small fin consists altogether of only fourteen radials, with fourteen elongated, 

 juxtaposed, median cartilages. All but the first two of these median cartilages have 

 distal ones attached to their summits ; and these, again, may be more or less segmented . 



There are but nine hasal cartilages, because the first two median cartilages have no 

 basal ones, while what should evidently be the four most postaxial basal cartilages have 

 coalesced into a small antero-posteriorly directed cartilage (5), the rudimentary repre- 

 sentative of the large basal cartilage of the dorsal fin of Noticlanus cinereus. This 

 small cartilage has a certain resemblance to a pectoral metapterygium. 



The whole fin-skeleton is separated from the axial skeleton by a considerable mem- 

 branous interval. 



The Ventral Fin (LXXV. fig. 7). 



This fin is supported by a series of sixteen continuous radial cartilages, attached to 

 an elongated basal cartilage {h), except the first (most preaxial) one, which joins the 

 pelvic cartilage {p). 



The distal ends of each of these cartilages, except the five most postaxial, bears a 

 distal cartilage, which may be once or even (as in the second) twice segmented. 



The Pectoral Fin (LXXVI. fig. 1). 



The somewhat complex skeleton of this fin is in one respect open to two interpreta- 

 tions ; the mesopterygium may be regarded as present or wholly or partly absent, there 

 being but two elongated basal cartilages, with an interposed membranous interval. 



As to the metapterygium there can be no doubt ; it is elongated, articulates proxi- 

 mally with the shoulder-girdle, is unsegmented, and supports ten radials. 



Between it and the next basal cartilage is a distinct membranous interval, which 

 cannot be regarded as other than the representative of the membranous interval, which 

 we shall find to exist in the pectoral of Chiloscyllium ocellatum (Plate LXXVI. fig. 4). 



The large elongated preaxial basal cartilage {p t) seems evidently the homologue of 

 that of Chiloscyllium, and may therefore possibly be the propterygium. But, just as in 

 Notidanus the great preaxiad cartilage seems to consist of part of the propterygium 

 in union with the mesopterygium, so here we may perhaps regard this cartilage as 

 answering to portions of both meso- and propterygia united. 



This complex cartilage has at its proximal end a small transversely extended cartilage 

 (/>') like the small similarly shaped proximal part of the propterygium of Notidanus. 



In Cldloscyllium ocellatum (Plate LXXVI. fig. 4) the most preaxiad radial creeps up 

 beside the preaxial margin of the propterygium to its middle ; but here two or three 

 preaxial radials, having more or less coalesced {cr), seem to creep up its preaxial edge, 

 and abut against the separate proximal piece of the propterygium, while a border of 



