COTTOMORPHS. 
193 
Subfamily T R I G L IN IE. 
Head cuirassed. Air-bladder present. 
The presence of the air-bladder and the appearance 
of the head, which is almost naked, but armed by the 
thickening and granulation of the external bones, to- 
gether with the fairly uniform covering of scales on 
the body, distinguish the subfamily of the Gurnards 
from that of the true Cottoids. In the preceding sub- 
family, however, we have seen numbers of intermediate 
forms between it and the Gurnards. In a specimen of 
Cottas claviger a great part of the head displays the 
same nakedness and the same granulation; but the most 
striking external similarity appears in the spines which 
occur along the base of the dorsal tins in Centrider- 
michthys hamatus , Cottas Lilljeborgii and the young spe- 
cimens of C. babalis. Similar spines are here a con- 
stant character of that genus which has given its name 
to the subfamily, and here they are firmly attached to 
the subjacent interspinal bones, a circumstance which, 
as a rule, renders their number constant in each spe- 
cies and equal to the total number of rays in the two 
dorsal fins. The difference between the upper and 
lower rays of the pectoral fins, which is wel 1 marked 
in the preceding subfamily, is here maintained in one 
of two ways: either some of the lower rays become 
free, digitate organs of touch and motion, or the upper 
(smaller) part of these fins (in Dactylopterus ) is wholly 
detached from the lower (posterior). In connexion 
with the cuirass of the head we find a marked de- 
velopment of the bones of the suborbital ring, which 
are firmly united posteriorly to the preoperculum and 
anteriorly cover the sides of the whole snout, projecting 
to a greater or less extent — in some forms like spa- 
tulate processes — beyond the snout itself, and at the 
same time covering the maxillary bones, when the 
mouth is closed. The development of the air-bladder 
constitutes a distinct difference from the preceding family: 
the sounds which the Gurnards are capable of producing 
much more generally and more loudly — a circumstance 
which has given them their Swedish name, knorrhanar 
(“Crooners”) — arise from or at least are intensified by the 
vibrations of the air-bladder. These vibrations are due 
to the strong contraction, accompanied also by rapid 
vibrations", of the muscular sheathing of the air-bladder 
itself, of the adjacent intracostal muscles or even of 
the large lateral and abdominal muscles. For the same 
purpose the air-bladder is furnished with special muscles, 
and also, probably for the same purpose, the property 
of changing the strength and tone of the sounds, gene- 
rally divided into chambers by a constriction, either 
anteriorly, as in Trigla gurnardas, or anteriorly and 
posteriorly, as in Dactylopterus : it may also have lateral 
processes, as in Trigla lucerna, in the form of long 
horns, lying along the sides*. The gill-openings are 
generally normal in these fishes; and there is a perfect 
branchial slit even behind the fourth branchial arch. 
Through the strong covering of scales on the body 
several of these fishes, notably Dactylopterus and Peri- 
stedion , come so near the following family ( Agonidce ) 
that they have sometimes c been referred to it; but the 
structure of the head and the air-bladder speaks in 
favour of their retention close to the Gurnards. 
The appearance of the Gurnards is peculiar, but 
their manner of life still more so. The Gurnards and 
Malarmats are really to be regarded a s bottom -fishes 
which use the free, lower rays of the pectoral fins as 
feelers in searching for food at the bottom, or even as 
creeping-organs, and which often betray, by the traces 
of wear in the points of the prominent preorbital bones, 
that these bones have been used to root up the bottom. 
But they are frequently found in the open sea, and 
are then scarcely inferior in swiftness of motion to 
a According to Dufosse. Linnaeus, in bis concise, but telling, style, described this sound with perfect fidelity to nature, and hinted 
at its source in Trigla gurnardus: “Captus in abdomine inurmurat, moribundus tremit” ( Fauna Suecica , ed. II, p. 120). Cf. also Moreau, 
Comptes Rendus, 1864, II, p. 436. 
6 Cf. Yarrell, British Fishes , ed. 2, vol. 1, p. 40; Kroyer, Danmarks Fiske, vol. 1, p. 116; Dufosse, Ann. d. Sc. Nat. ser. 5, 
Tome XIX (1874), art. No. 5, pp. 38 etc., pi. 16 — 19; Tome XX (1874), art. No. 3. pp. 47 etc.; Sorensen, Om Lydorgancr hos Fiske, 
p. 129. 
c Gunther, Introd. Stud. Fish., p. 481 ( Handh . Ichtliyol., p. 341). 
Scandinavian Fishes. 
