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XII. Notes on the Fins of Elasmobranchs, with Considerations on the Nature and 
Homologues of Vertebrate Limbs. By St. Groner Mivart, V.P.Z.S. 
Received December 22nd, 1877. Read February 5th, 1878. 
[Puates LXXIV.—-LXXIX.] 
IN the following paper I describe certain fin-structures which I have not found to be 
described elsewhere. 
Before proceeding to do so, however, I must express my grateful sense of the kindness 
of my friend Dr. Giinther in placing at my disposal for examination and illustration 
duplicate store-specimens of Elasmobranchs which I should otherwise have had no 
means of investigating. The species referred to are Zygwna malleus, Mustelus antarc- 
ticus, Notidanus cinereus, Scyllium canicula, Ginglymostoma cirratum, Chiloscyllium 
ocellatum, Acanthias blainvillii, Spinax niger, Pristiophorus japonicus, Pristis cuspidata, 
Rhynchobatus djeddensis, Trygonorhina fasciata, and Callorhynchus antarcticus. 
Besides these, I have made use, for comparison, of certain skeletons preserved in the 
Museum of the Royal College of Surgeons, drawings of some of which have been made 
through the kind permission of my friend Professor Flower and the other authorities 
of that Institution. These are Lamna cornubica, Cestracion philippi, Squatina angelus, 
Polyodon folium, and Polypterus bichir. 
It may be well first to describe the specimens examined, and then to make such 
remarks as have suggested themselves in regard to Vertebrate limbs generally, and 
the relations borne by the fins of fishes to the extremities of higher animals. 
ZYGHNA MALLEUS. 
Dorsat Fin (Plate LX XIV. fig. 1). 
The dorsal fin in this species is sustained by a great number of very elongate and 
closely set cartilaginous rays, or, as they may be for distinction termed, “ radials.” 
which form three superimposed longitudinal series—one basal, one median, one distal. 
The number of these radials bears, as far as I can perceive, no exact relation to the 
number of subjacent vertebra ; and the whole fin-skeleton is separated from the sub- 
jacent axial skeleton by interposed fibrous membrane, the interval, however, being 
less wide than half the depth of the shortest of the three superimposed series of 
cartilages. 
The Jasal cartilages are twenty-six in number ; but the second and the eighth from the 
preaxial end of the series bifurcate distally, and the last but one seems to be made 
Vou, X.—part x. No. 1.— February 1st, 1879. 30 
