OP AH. 
125 
rays at the beginning of the dorsal fin, the first is 
extremely short, and united to the base of the second, 
which in the specimen belonging to the Royal Museum 
is broken oft' short, but according to Lowe is the 
longest ray in the whole fin. A peculiar, falciform, 
interspinal bone, with the concave margin grooved, 
lies loose in the flesh between the occiput and the 
first dorsal fink The first true interspinal bone is both 
long and high, with the curved anterior margin dilated 
and with several pairs of lateral ridges, the posterior, 
in particular, high and sharp, but less so than on the 
eight next following interspinal bones. The interspinal 
bones are gradually reduced in length in the same 
proportion as the length of the rays in the dorsal fin 
from the first branched ray to the twelfth. The neural 
spines in the abdominal region, on the other hand, 
become longer posteriorly. The dorsal fin in form 
resembles that of the Swordfish: behind the elevated, 
falciform, anterior part follows a low portion, from the 
fourteenth ray to the seventeenth inclusive, in the spe- 
cimen of the Royal Museum, and then the fin again 
rises, though slowly and inconsiderably. The anal fin 
throughout its length resembles the posterior part of 
the dorsal. The lateral line is sharply curved in an 
elevated arch anteriorly, and then runs straight along 
the body in the middle line of the depth. 
The Opah is one of the deep-sea fishes of the 
Atlantic, known from Norwegian Finmark, Iceland and 
Newfoundland at least as far south as Teneriffe, and 
also occurs in the Mediterranean, but is generally very 
rare. In Madeira, however, according to Lowe, it is 
fairly often brought to market during spring. It can- 
not, however, be reckoned among the inhabitants of 
the deepest regions, as seaweeds are occasionally found 
with other food in its stomach. Its food consists chiefly 
of cuttlefish, thin-shelled Isopods which have their home 
in the algae, Herrings and, probably, other small fishes. 
It is caught off Madeira, says Lowe, with hooks baited 
with Mackerel or Scad, at a depth of from 50 to 100 
fathoms. This depth, if indeed it be the Opah’s pro- 
per home, is great enough to prevent it from moving 
freely at its pleasure at the surface*, when for some 
reason or other it suddenly rises into the higher re- 
gions of the ocean. Thus, like other deep-sea fishes, 
it is often found floating helplessly at the surface or 
cast ashore by the waves. It attains a length of about 
4 7 a feet (1 V 2 metres)' 7 ; but most of the specimens 
known have measured between 3 and 4 ft. in length. 
Its whole body is very fat, and its flavour is compared 
by most of those who have tasted it, to that of the 
Salmon; but Mr. Olsen writes to me that a part of 
his Opah tasted like beef, another part like veal, a 
third like brain, and a fourth like “fish.” In Madeira, 
says Lowe*, the flesh of the Opah is considered better 
and costs more than that of the Tunny. “Formerly, 
I am informed, it was held in such esteem that every 
fish taken was obliged by law to be carried to the 
governor of the Island, without whose licence it could 
not be sold in the market. ’ 
In Norway the Opah is rare, but according to 
both Lilljeborg and Collett a specimen is taken al- 
most every year in the neighbourhood of Bergen. So 
early a writer as Peder Claussen 7 knew it from Nord- 
land and called it u den shone Laxestorje (the beautiful 
Great Salmon). It has been met with several times 
in Christiania Fjord and, strangely enough, off the 
coast of Zealand and near Helsingborg. It was from 
the last place that Retzius described it for the first- 
time as a Swedish fish. We have fewer mentions of 
it from Bohuslan; but according to Malm it is known 
to a few of the fishermen by the name of “ makril - 
storje”. Ekstrom (1. c.) mentions a specimen which 
was caught in the forties in the neighbourhood of 
Stromst-ad; and the specimen of the Royal Museum 
which we have already mentioned, was taken at the 
beginning of August, 1873, by some fishermen from 
a Cf. Lowe, 1. o., p. 29. 
6 Cf. Lowe, 1. c., p. 34. 
c See above, under Genua Caranos. 
d Baikie (Zool. 1853), according to Day (1. c.), meutions a specimen 6 ft. long, which was caught off Sanday, one of the Orkneys. 
The specimen mentioned above which was examined by Olsen, he states to have measured 5 ft. in length, 3 ft. in depth and 10 in. in 
thickness. 
e 1. c., p. 35. 
f Norriges Bescriffuelse , Kjobenhaffn 1632, p. 120. 
