482 PROF. ST. GEORGE MIVART ON THE 
set of parts (pterygia), for the sum total of which the term sympterygiuin 
may be employed. 
(2) Piscine fins are related to the limbs of higher vertebrates as structures which 
have diverged to a less degree from their primitive condition—and this not 
only because the piscine body, as a whole, is a more primitive structure, but 
also because their fins are still used for locomotion in that medium in which 
their primeval form, the continuous lateral fold, was first developed. 
DESCRIPTION OF THE PLATES. 
PLATE LXXIV. 
g. 1. First dorsal fin of Zygena malleus. 
Fig. 2. First dorsal fin of Lamna cornubica. 
3. First dorsal fin of Mustelus antarcticus. 
4. Left pectoral fin of ditto. 
a, propterygium ; 4, mesopterygium ; c, metapterygium. » 
Fig. 5. Left ventral fin of ditto. 
p, pelvic cartilage. 
Fig. 6. Caudal fin of ditto. 
/p, parapophysial vertebral elements. 
PLATE LXXYV. 
Fig. 1. Caudal fin of Lamna cornubica. 
Fig. 2. First dorsal fin of Votidanus cinereus. 
b, basal cartilage. 
Fig. 3. Left pectoral fin of ditto. 
a, propterygium ; 6, mesopterygium ; c, metapterygium. 
Fig. 4. Left ventral fin of ditto. 
b, basal cartilage ; p, pelvic cartilage. 
Fig. 5. Anal fin of ditto. 
Fig. 6. First dorsal fin of Seyllium canicula. 
Fig. 7. Left ventral fin of Ginglymostoma cirratum. 
b, basal cartilage; p, pelvic cartilage. 
PLATE LXXVI. 
Fig. 1. Left pectoral fin of Ginglymostoma cirratum. 
er, coalesced radials; p', small proximal piece; pt, propterygium ? 
