PROCEEDINGS OF SCIEN'TIFIC SOCIETIES. 345 
Mr. F. M. Balfour read a paper on the development of the skeleton of 
the paired fins of the Elasmobranchs, considered in relation to its bearings 
on the nature of the limbs of the Vertebrata. The object of the investiga- 
tions recorded in this paper was explained by the author to be twofold— 
viz., on the one hand, to test how far the study of the development of the 
skeleton of the fins supported the view which had previously been arrived 
at by the author, to the effect that the paired fins were the specialised and 
highly developed remnants of a once continuous lateral fin on each side; 
and, on the other, to decide between the views of Gegenbaur and Huxley 
aud Thacker and Mivart as to the primitive type of fin-skeleton. The 
author pointed out that the results of his researches were entirely favourable 
to the view that the paired fins were structures of the same nature as the 
unpaired; and that they gave a general support to the views of Thacker 
and Mivart. They clearly showed that the pelvic fins retained more 
primitive character than the pectoral. Conclusions were drawn somewhat 
adverse to the views recently put forward on the structure of the fin by 
Gegenbaur aud Huxley, both of whom considered the primitive type of fin 
to be most nearly retained in Ceratodus, and to consist of a central multi- 
segmented axis with numerous rays on its two sides. It appeared, in fact, 
that the development of the skeleton demonstrates that a biserial type of 
fin like that of Ceratodus could not have been primitive, but that it must 
have been secondarily derived from a uniserial type, by the primitive bar 
along the base of the fin (the “ basipterygium”) being rotated outwards, and 
a second set of rays being developed on its posterior border. 
Mr. W. T. Blanford read some notes on a collection of Persian Reptiles 
recently added to the British Museum, amongst which was an example of 
a new species of Lizard, proposed to be called Agama persica. 
A communication was read from the Rev. O. P. Cambridge on a new 
Spider of the family Theraphoside. ‘The chief interest attaching to this 
Spider was the fact that it had lived in the Gardens of the Society from 
March to October, 1880. Mr. Cambridge proposed to name the species 
Homeomma Stradlingii, after Dr. Stradling, who had brought home from 
Bahia the specimen in question. 
Mr. G. E. Dobson read a paper ov the pharynx, larynx, and hyoid 
bones in the Hpomophori, indicating some very remarkable peculiarities 
of structure, in which these Bats appear to differ not only from all 
other Chiroptera, but from all other mammals. Pharyngial air-sacs 
were also described in the males of Hpomophori monstrosus, franqueti, 
and comptus. 
Mr. J. Gwyn Jeffreys read the third of the series of his memoirs on the 
Mollusca procured during the ‘ Lightning’ and ‘ Porcupine’ expeditions 
1868-70. The present paper contained an account of the families from 
Kelliide to Tellinide. Eleven new or hitherto unfigured species were 
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