310 
SCANDINAVIAN FISHES. 
and are more or less helplessly driven ashore by wind 
and tide. We have already quoted from Gunther some 
of the most important, general characteristics which 
belong to the deep-sea fishes. One of these character- 
istics, the loose structure of the body, both in the 
osseous and muscular texture, appears in a high degree 
in the Trachypteroid family. The larger forms at least 
— some of the Trachypteroid s attain a length of at 
least 6 metres — are so fragile that even with the 
greatest caution it is scarcely possible to draw a spe- 
cimen out of the water without damaging some part 
of it. Still less can we expect that a specimen cast 
ashore by the storm and exposed to the action of the 
waves, may be found in a perfect condition. Further- 
more, the tins and their appendages undergo changes 
of growth so great that it is by no means always pos- 
sible to decide with certainty whether the loss of a, 
character derived from these parts of the body is the 
result of some injury or merely of the natural develop- 
ment. The specific distinction within this family is, 
Fig. 76. Young Trachypterus , 3 mm. in length. After Emery. 
therefore, far from certain, and the majority of the 
species established by former writers up to the time of 
Valenciennes'' and recognised even in Gunther’s Ca- 
talogue , have been rejected or proposed for rejection in 
more recent times. The history of the development has 
shown a variability scarcely conceivable before, in the 
supposed specific characters. The pioneer of this reform 
is the Italian Emery*, who enjoyed the most favourable 
opportunities of studying the young of these fishes, as 
they appear in the surface-regions of the Mediterranean. 
The first stage in the development of a Trachm 
pterus described to us by Emery (fig. 76), is a larva 3 
mm. in length. At this period it is perhaps most like 
the larva of a Coitus or a Lophius. The head is large, 
and the long caudal part sharply contrasted to the much 
deeper abdominal region. The whole body is trans- 
parent. The embryonic vertical fin runs without a 
break along the margin of the body, from the head 
along the back and round the tail to the end of the 
abdominal part. At the occiput this tin contains the 
rudiments of three true rays, with this exception it is 
without rays, and is supported only by the primary 
rods (fibrillae). The pectoral fins are comparatively 
large, with a brachiate base, and edged with a rim of 
the same structure as the vertical fin. The rudiments 
of the ventral fins appear in the form of a process on 
each side, projecting backwards from the lower pos- 
terior corner of the abdominal part. 
In the next stage described by Emery (fig. 77), 
the larva has attained a, length of 6 mm. It is now 
tadpole-like, and the first three rays of the dorsal fin 
have grown beyond the fin-membrane, thus reminding 
us of the Batrachoids. Behind them three new rays 
have begun to appear, and the embryonic vertical fin 
Fig. 77. Young specimen of Trachypterus , 6 mm. in length. 
After Emery. 
has grown to such a height on the caudal part that 
the hind part of the larva is nearly as deep as the 
forepart. The rudiments of the pectoral and ventral 
fins have also grown. The whole larva is still trans- 
parent, but finely punctated with small, brown collec- 
tions of pigment, forming two transverse bands on the 
caudal part. 
In a larva 9 mm. long, which was brought home 
by Professor Leche from Messina, the caudal part of 
the body itself is still terete and of an elongated, con- 
ical shape. The occiput is raised as in Lophotes. 
The dorsal fin has begun to acquire rudimentary rays 
throughout the greater part of its length from the 
occiput. The anterior dorsal rays have attained a, length 
Gen. Trachypterus, p. 14, tav. IX ter), the first ventral ray in Trachypterus repandus ( iris ?), a Mediterranean form, is divided at the tip 
into four membranous filaments (see fig. 81, a). With these exceptions little is known of the structure of the ventral rays in ihe older spe- 
cimens, as they easily and generally break or drop off. During youth, however, and even in specimens 32 cm. long, they are unbranched in 
the specimens we have examined of the Mediterranean species Trachypterus iris. 
a Cuv., Val., Hist. Nat. Poiss., vol. X, pp. 313 etc. 
b Atti Accad. Line., ser. 3, Mem. Sc. Fis., vol. III. p. 390, con tav.: Mitth. Zool. Stat. Neap., Bd. I (1879), p. 581, tab. XVIII. 
