SCOMBROMORPHS. 
69 
the spines of the head which generally appears with age 
— the branched preorbital spines are those which still 
remain longest and strongest, while the spines on the 
nasal bones and on the forehead between the eyes al- 
most disappear, and the spine at the lower posterior 
corner of the branches of the lower jaw becomes in- 
significant — we must also assign the almost complete 
disappearance of the bony ridge on the operculum, 
which in several of the preceding forms we have seen 
prolonged into a spine at the hind margin. It should 
also prove interesting to examine some young specimens 
in order to see whether the two “sharply denticulated 
ridges” which occur at the rounded corner of the pre- 
operculum, do not correspond in their development to 
some evanescent spines on the same bone. The denta- 
tion of the scales of the body seems also to undergo 
a completely analogous diminution as the fish grows 
older. Their free surface, above and below the longi- 
tudinal groove, is fringed in youth with from 16 to 20 
or more rows of spines, which afterwards change into 
denticulated ridges and finally into still smoother bars, 
a difference which may also be observed to exist be- 
tween the scales of the back and cheek and those of 
the belly. All these changes indicate that Beryx, though 
one of the oldest generic forms and though it retains 
the original type of the family in some respects, has 
still passed through changes of form which mark such 
stages of development as other, apparently younger 
genera, e. g. Hoi o centrum, have never surmounted. 
Beryx decadactylus, which attains a length of about 
52 cm., is one of the rarest of fishes, not only in Scan- 
dinavia, where only 3 specimens have been found and 
these confined to the neighbourhood of Bergen and 
taken at a depth of 200 fathoms, but also in the deep 
water between the Canary Islands, Madeira, the Azores 
and Portugal, the other locality where it has been met 
with in the Atlantic. There is a significant peculiarity, 
however, in connection with its geographical range, not 
only that it thus lives in so far distant parts of the 
Atlantic, a proof of the fact that the deep-sea fauna is 
uniform and made up of hardy, primitive forms, but 
also that it forms a connecting link between the fauna 
of the Mediterranean region and the Sea of Japan. 
Doderlein and Steindachner include this species", 
together with B. splendens among the fishes of Japan. 
As an explanation of this find and other similar ones, 
Gunther’s* remark as to the still more remarkable range 
of certain shore fishes must not be forgotten": “Bold 
as the hypothesis may appear, we can only account for 
the singular distribution of these shore-fishes by as- 
suming that the Mediterranean and Japanese seas were 
in direct and open communication with each other 
within the period of the existence of the present Te- 
leosteous fauna.” 
SCOMBROMORPHI. 
A f usiform body ■with a narroiv (low), round peduncle of the caudal fin , a skin often naked or only partly covered 
with thin , cycloid scales, a weak dental equipment of the mouth, no denticulation of the preoperculum in adult speci- 
mens, iveak spinous rays in the dorsal and anal fins and pointed (typically falciform) pectoral finis and caudal -flaps 
form the general distinctions between the series of the 
Mackerel and Perch families. But the former, as well 
as the latter, in contradistinction to the Anomalopte- 
rous families, are stenobrachii and furnished with nu- 
merous rays in the caudal fin (euryripidi). 
We have already seen the principles on which a 
series of the Acanthopterygian Teleosteous families 
might be grouped round the Mackerel-form as their 
type. But there are important deviations from this 
type within the series itself. Sometimes the 1 tody is 
naked, sometimes covered with large scales; sometimes 
it is long and low, sometimes high and compressed; 
but these different forms are systematically connected, 
partly by changes of development (growth) and partly 
by intermediate forms even in the same family. The 
character which may most generally be employed, is 
one that in other cases where the distribution is so 
wide, is scarcely applicable, namely, the sharp-pointed 
form of the feebly-supported fins, especially the pectoral 
and caudal. But even this character must lose its 
3 Denkschr. Akad. Wiss. Wien, Mat. Naturw. CL, Bd. XLVII, pp. 220, 221. 
6 Provided it cannot be proved that both these “species” are cosmopolitan deep-sea fishes. 
c Introd. Study of Fish., p. 270; Handb. Ichthyol ., p. 181. 
