444 PROF. ST. GEOEGE UnVAET ON THE 



The Ventral Fin (Plate LXXV. fig. 4). 



The ventral-fin skeleton consists of a closely set series of rays, nineteen being attached 

 to an elongate basal cartilage (b), and the remaining four (mostly much shorter) more 

 preaxial rays being attached to the pelvic cartilage (j}). Very short, more distally 

 situated cartilages are attached to and between the distal ends of the more proximal 

 rays ; and there is a trace of yet another, third, or most distal series, in the form of five 

 minute cartilages, situated, again, between the more preaxial (excepting the first) of 

 the small cartilages just described. The general resemblance of this structure to that 

 of the dorsal fin is very noteworthy. 



The Anal Fin (Plate LXXV. fig. 5). 



Here we have again a closely set longitudinal series of eighteen cartilaginous rays, 

 or radials, attached to a more solid basal structure. The seven more preaxial rays are 

 much larger than the succeeding ones ; always segmented, they are somewhat irregularly 

 so. The succeeding more slender rays are not all segmented. The nine most postaxial 

 rays are attached to one large and long continuous basal cartilage. The next six have 

 a solid cartilaginous support for each pair. The ray next preaxiad has a cartilaginous 

 support to itself, preaxial to which the basal cartilage seems irregularly segmented, 

 longitudinally as well as vertically. The base of this fin has every appearance of having 

 been formed by the coalescence of the basal parts of its constituent radials. 



The Pectoral Fin (Plate LXXV. fig. 3). 



The proportion borne by the basal cartilages, as a whole, to the rays is very large in 

 the pectoral of this species. 



The nietapterygium {c) is very elongated, very narrow, and once segmented towards its 

 proximal end. It expands greatly distad. It supports fifteen radials. 



The meso]}terygium (b) is also very large, triangular, with its shortest side proximad. 

 It supports ten radials, including the most preaxial ones, as it extends to the preaxial 

 margin of the limb ; on which account I am disposed to regard this cartUage as consist- 

 ing of mesopterygium, with the distal part of a segmented propterygium confluent with 

 it. Indeed I know of no definition applicable to these cartilages, save what can be 

 drawn from their position with respect to the limb-axis. 



The ])ro]jtery(jium (a) — or, if the view above stated is correct, the proximal part of 

 the propterygium — is exceedingly small, broader than long, and is entirely excluded 

 from the radials by the extension preaxiad of the mesopterygium to the preaxial 

 margin of the limb. 



I find the first (most preaxiad) radial to be, in the specimen depicted by me, slightly 

 the broadest at its base, and to consist of four segments ; but the segments of the 

 radials generally are somewhat irregular. Those attached to the mesopterygium are 



