at 
— 
ON A TELEOSTEAN FISH. 2 
16. The Structure and Development of the Caudal Skeleton 
of the Teleostean Fish, Plewragramma antarcticum. By. 
A. Kyyvert Torton *. 
[Received December 17, 1913: Read March 17, 1914. | 
(Plates I. & II.) 
INDEX. Page 
Mionpholo cyt istiakea: 2 aa: neuen ieee ae watneciaeat ate EOS! 
evelopment. hese a Aare Lh etgae aeea espana ann OL 
In this paper I have recorded several points of interest in 
connection with the development of the vertebral column of a 
Teleostean fish, Plewragramma antarcticwm. My material con- 
sisted of a collection of the post-larval stages collected on the 
Southern Cross Expedition, and handed over to the Imperial 
College of Science for description on behalf of the Trustees of the 
Natural History Museum by Professor Jeftrey Bell, to whom 1 
here wish to express my thanks. ‘lo Professor EH. W. MacBride, 
F.R.S., V.P.Z.S., at whose suggestion I undertook this piece of 
work, and under whose supervision it has taken its present form, 
and to Mr. H. G. Newth, for very much useful help, my thanks 
are due and are very gratefully tendered. 
Unfortunately the Plewragramma material does not contain 
stages quite late enough to show the actual formation of centra, 
though the largest specimens are about 4°5 cm. long, 
I believe that no specimens of this fish have been taken inter- 
mediate in size between those at my disposal and certain speci- 
mens—adults 16-17 em. long, taken from the stomachs of Seals,— 
one of which Mr. Tate Regan very kindly allowed me to examine, 
together with a specimen of Zrematomus newnesii, a closely allied 
species in which the notochord is relatively smaller and the centra 
better ossified than in Plewragramma antarcticum. 
The fixative used in most cases appears to have been formalin 
or spirit, so that the material is not very good from a histological 
point of view. 
Pleuragramma antarcticum is a specialised Teleost of the family 
Nototheniide, the genus differing from the related Antarctic 
genus Zrematomus chiefly in the feeble ossification of the skeleton. 
Boulenger included Pleuragramma in the family leptoscopide, 
but Regan has pointed out that it does not resemble Lepto- 
scopus, but, on the other band, is very near Zrematomus. Most 
of the Nototheniiform fishes are littoral and feed on crus- 
taceans, molluses, ete. Zrematomus newnesti and Pleuragramma 
antarcticum are amongst the more southern types, and appear to 
be circumpolar (cf. Regan, Trans. R. Soc. Edinburgh, xlix. 1913, 
pp. 251, 257, 264, &e.). 
* Communicated by Prof. E. W. MacBripg, D.Se., F.R.S., V.P.Z.S. 
+ For explanation of the Plates see p. 260. 
