582 
SCANDINAVIAN FISHES. 
body, Gunther’s Macrurus eras sleeps a from the deep- 
sea fauna of Australia. 
In 1884 Professor Leche took a specimen of a Krohnius- form at 
the surface off Messina. This specimen (fig. 138) has advanced so 
far in development that we need not hesitate in referring it at least 
to the genus Macrurus. Including the very fine tip of the tail the 
specimen measures 92 mm., the forepart of the body being 12 mm. 
long, 9 mm. deep, 6 mm. broad, clumsy, and almost spherical, while 
behind this point the strongly compressed tail begins with a depth of 
4 ■’A nun. and very gradually tapers to a filamentous, narrow but com- 
pressed, and membranous appendage. This appendage, which is I 8 V 2 
mm. long, forms a slight break at its insertion in the tip of the tail 
and advances straight back, marked with dark reddish brown spots of 
pigment, small, but dense, and set in two rows at the base of the 
appendage, in one row, more scattered, and larger (finally occupying 
the entire breadth of the appendage) towards its tip, which is, how- 
ever, colourless. The head does not measure even half of the bulky 
forepart, though its length, measured as usual from the tip of the 
snout to the hind margin of the gill-cover (obliquely against the lon- 
gitudinal axis of the body), is 6' 2 / 3 mm. From the same cause the 
length of the snout becomes fairly great, measuring 1 */ 5 mm., although 
the round eyes, with a longitudinal diameter of 2 mm., and set at a 
distance of about 2 mm. from each other, evidently lie far forward. 
The postorbital part occupies about half the length of the head, or 3Y 5 
Fig. 138. Krohnius f larnentosus, natural size. From Messina, Feb., 1884, 
V. Leche. Original in the possession of the High School of Stockholm. 
mm. The mouth is both terminal and lateral, with sharply ascending 
cleft. The maxillary bones end almost below the middle of the eyes. 
Below the chin there hangs a barbel about equal in length to the 
diameter of the eye. The nostrils are set on each side at the upper 
anterior corner of the eye, in a common opening, divided into two 
parts by a thin partition-wall. The first dorsal fin begins at a distance 
of 7 mm. from the tip of the snout, or a little behind the head. It 
is high — the longest ray measuring about 7 1 ( ' 2 mm. — -and pointed, 
almost falciform ; but the anterior rays (except the first, which is 
rudimentary) are elongated into filaments. The fin contains one rudi- 
mentary ray and nine perfect, but simple rays. The length of its 
base is 2 1 / , 2 mm., or somewhat more than the longitudinal diameter of 
the eyes. Behind this fin the dorsal edge still retains a low dermal 
flap, a remnant of the embryonic vertical fin, and distinguishable not 
quite to the end of the bulky forepart. At this point the flap dis- 
appears, but soon returns again, though at first scarcely distinguishable, 
at about the end of the swollen forepart of the body, now with true 
rays and in the form of a second dorsal fin, which is remarkably low 
and follows the dorsal edge back to the base of the caudal filament. 
The anal fin begins at a distance of 11 mm. from the tip of 
the snout, on the posterior part of that which we have termed the 
swollen forepart of the body. Its base thus follows the ventral margin 
backwards and upwards, then passing in a rounded obtuse angle to 
the ventral margin of the caudal part, and following the latter to its 
termination. The rays of the anal fin, which, like those of the dorsal 
fins, are all simple, first increase in length uniformly but sharply, the 
length of the rays at the beginning of the tail being about equal to 
the depth of the latter. Thus the margin of the anal fin is fairly 
straight, in spite of the sinus in the margin of the body at this spot. 
From this point the rays gradually decrease in length, until at the 
beginning of the posterior half of the tail their length increases some- 
what, the height of the anal fin being here greater than the depth 
of the tail; but towards the tip of the tail the length of the rays 
again decreases. At the base of each ray of the anal fin we find a 
dark-brown, pigmental spot. The pectoral fins are perhaps the most 
characteristic peculiarities of this larva. They are almost semicircular 
disks, for the greater part free, attached to the shoulder-girdle only 
at the top by a narrow shaft, which is inserted on about a level with 
the middle of the eye. The outer part of these disks is extremely 
thin and membranous, but with rudiments of the future pectoral rays ; 
the inner part is somewhat thicker, in the specimen preserved in spi- 
rits opaque, and is of an almost regular, but flattened kidney-shape, the 
upper corner of which, situated about one-third of the way up the 
pectoral fins, forms the point of origin for the said shaft. If we com- 
pare this form of the pectoral fins with their arrangement in certain 
Codfishes, where the internal structure is known * 6 , it appears extremely 
probable that the shaft corresponds to the rudiments of the proximal 
parts of the shoulder-blade and the coracoid bone, while the distal parts 
of these bones and the basal bones of the pectoral rays are developed 
in the kidney-shaped part of the base of the pectoral disk. Shafted 
(lobate) pectoral fins are indeed by no means rare in the fry of other 
species 0 ; but a shaft so long and so narrow as in this larva — remind- 
ing us of the elongation of the basal bones in Lophius — is unparal- 
leled within our experience. The ventral fins are set vertically below 
the insertion of the pectoral fins, somewhat in front of the middle 
point between the tip of the snout and the anal fin — the foremost 
point of their insertion lies at a distance of 6 mm. from the beginning 
of the anal fin — and are remarkable for the great elongation of the 
six middle rays. The first ray is not short, its length being very 
nearly as great as that of the head; but the next 6 rays attain a length 
of as much as 30 mm., are pigmented in the outer part in the same 
way as the caudal filament, and are also flattened throughout their 
length like this filament. The innermost two rays are short, the inner- 
most ray the shortest of all. The anal aperture lies about half-way 
between the insertions of the ventral fins and the beginning of the 
anal fin; it has a pointed anal papilla behind it. Half-way between 
the ventral fins and the isthmus we find a round depression in the 
ventral wall, coasted in front by a semicircular, membranous, dermal 
swelling, the two ends of which are continued each by a dermal ridge 
which disappears behind. This structure evidently bears the appearance 
of having served as an adhesive apparatus by means of which the larva 
has been enabled to attach itself to floating objects, and is probably 
of importance as an explanation of the bare (scaleless) spot which in 
adult examples of some species of the genus occurs on this part of 
the body. On the upper portion of the abdominal sides the scales have 
apparently begun to develop; but the rest of the body is naked. 
It is difficult as yet with certainty to determine the species of 
this larva. Among the four Mediterranean species of the genus given 
by Giglioli d , it can hardly be referred to any other than Macrurus 
Icevis. This opinion is borne out both by the number of rays in the 
“ Deep Sea Fish., Chall. Exp., p. 143, pi. XXXVII. 
6 See for example Emery, Fierasfer in Fauna und Flora des Golfes von Neapel, II Monogr., p. 29, taf. IV, fig. 40. 
c Cf. above, fig. 77, p. 311. 
d Espos. Intern, di Pesca, Berlino 1880, Sez. Ital. Cat., p. 98. 
