296 , Transactions.—Z oology. 
Pseudo-branchise well-developed. Pyloric appendages in moderate num- 
bers; ova small. 
Marine fish which never enter fresh waters, and hitherto found only in 
some parts of European waters, i.e., coasts of Norway, rarely coasts of 
Scotland and islands and the Mediterranean. 
Argentina decagon, nov. sp. 
D.10, 2nd adipose; P.14; V.12; A.11; C.19; B.5; L. Trans. 1; 
L. Lat. 51. * 
First dorsal situated in depression on back ; adipose dorsal high ; pectorals 
small, fragile; ventrals rather large, fragile, large axillary scale; caudal 
large, deeply forked; eye large, round; mouth very small, and protractile 
to some extent; anal fin very high anteriorly (this fin and adipose dorsal 
placed close to caudal; cheeks and head scaleless, top of head flat, head 
small, snout pointed; operculum, suboperculum and preoperculum covered 
with thick transparent (immaculate) glossy flesh (showing colouring pig- 
ment on bony plates in a very beautiful manner) ; lower angle of preoper- 
culum and interoperculum free from fleshy substance; nostrils small, 
double, one placed before vertical of front of orbit, the other near tip of 
snout; back, belly and sides rather flattened, but body thick. 
No teeth on superior or intermaxillaries or on inferior maxillaries, but 
the front edge of vomer is produced and bare and crenulated, forming dental 
apparatus ; edges of palatines bared, forming cutting apparatus; tongue 
long, thin, narrow, and round, with four long recurved fangs at tip; gill- 
arches armed with long rakers; gills four and one pseudo- gill; upper jaw 
projects slightly over lower. 
Head rounded under throat; eye large; gill-opening large, section 
through body shows same to be an irregular decagon in shape. 
Scales (in beautifully arranged series) very large, thin, and covered with 
silvery pigment on lateral band, very bright, duller on series superior and 
inferior to same. Scales along lateral line high and narrow, with large 
core, the opening of which is directed towards head. At the angles of the 
irregular decagon the scales are large, squared in front, rounded at back, 
and bent in an angular form with an opening or slit extending some 
distance into scale. These scales overlap in the centres of the facets of the 
decagon, and over these, and extending nearly from angle to angle, are, on 
the dorsal, second, third lateral band and ventral facets superposed, large 
deep rounded scales filling up intervals between angles of decagon, and 
causing the ribbed appearance of body; the depression at lateral line is also 
caused by these large scales overlapping in unbroken marginal line, above 
and below same, 
