Plectognaths.- 
-FISHES- 
-Baiastids. 
hensile tails. The rings are numerous, and various 
knobs on the cranial bones, with the elongated face, 
produce a resemblance to the head of a horse, which 
was recognized in ancient times, as it is now by the 
present inhabitants of the Mediterranean, by the appel- 
lation of Sea-horses. Pliny, referring to these fishes, 
says — “ As, according to the common opinion, every- 
thing that is prodnced on land has its marine repre- 
Pig. 44. 
Falkland Island Nerophis (Nerophis liymeuolomus). 
sentative, our wonder ought to be the less on beholding 
the heads of horses springing from such tiny shells.” 
The genera are — Hippocampus; Acentronura; Gasieroto- 
keus; Soknopnatlius ; Phyllopteri/x ; Halicampus; Trachy- 
rhamphus ; Coryihoichthys ; Ichthyocampus ; Synyriaihus ; 
Leptonotus ; Siphonostomus ; Leptoichthys ; Stigmatophora ; 
Doryrhamplias ; Doryichthys ; Choeroichthys ; Hemithylacus ; 
Microphis ; and Nerophis. 
These, distributed into four subfamilies or tribes, are 
described by Dr. Kaup in his Catalogue of Fish in the 
British Museum. The following are British species — 
The Short-nosed Hippocampus {Hipypoca-inpus hrevi- 
rostris)\ the Needle-fish acMs); the Deep- 
nosed Pipe-fish {Siphonostomus typhle) ; the HSquoreal 
Pipe-fish {Nerophis cequoreus) ; the Snake Pipe-fish 
{Nerophis anguineus) ; the Straight- nosed Pipe-fish 
{Nerophis ophidion) ; the Worm Pipe-fish {Nerophis 
lumbnciformis ) . 
In the Edinburgh New Philosophical Journal for 
April, 1855, there is a statement of the ship Harbinger 
having sailed for several hundreds of miles in the 
North Atlantic among shoals of dead fishes, supposed 
to have been killed by submarine volcanic action. ( Ae 
of these dead fish being sent to Sir William Jardine, 
was determined by him to be the common Snake Pipe- 
fish {Nerophis anguineus). 
Order VIIL — PLE CTOGN AT H S. 
In this order the maxillary bone is soldered to or 
coalescent with the premaxillary of the same side, and 
in some groups the conjoined bones of the one side are 
blended on the mesial line with those of the other, 
forming a solid upper jaw in which the teeth are incor- 
porated, and which is opposed to a mandible of similar 
form and dentition, having its limbs also coalescent at 
the symphj'sis. In other groups the mesial junction of 
the lateral halves of the jaws is in form of a serrated 
suture. The internal skeleton is partially ossilied, and 
has a fibrous osteoid structure, without any bone cor- 
puscles. The pieces of the skeleton are fewer than in 
the Osseous fishes, having only rudimentary ribs, as 
well as wanting some other bones; and the dermal 
skeleton ditfering much in aspect from the ordinary 
scales, is considered to approach ganoid scales in tex- 
ture. The spines of the fins also, when present, are 
studded with ganoid grains. Agassiz, because of the 
structure of the dermal bony scales, is inclined to range 
the order provisionally among his Ganoids ; but Muller, 
who relies more on the forms of the central organ of 
circulation, does not separate the group from the Osseous 
fishes, with which its members agree in having merely 
two valves at the origin of the arterial stem, without 
the succeeding rows that exist in the Ganoids. The 
swim-bladder of these fishes is closed, having no air- 
duct, and there are no panc-reatic caeca. The gills are 
biserial, and the processes of one series alternate with 
those of the other instead of being in opposite pairs. 
There are no distinctly-developed ventrals, but their 
place is supplied in some groups by a projection of the 
pubic bones, sometimes followed by a longitudinal series 
of short slender spines. 
Family I. — BALISTIDS {Balistidce). 
Plate 13, fig. 65. 
The characters of this group are a conical face with 
a small mouth at its apex, armed with a few more or 
less tapering incisorial teeth. Tire skin is protected 
by shield-like, ganoid scales, or by small rough points. 
The branchise are three only. These are most gene- 
rally considerably compressed fishes, with a profile often 
approaching to oval or orbicular, but sometimes much 
elongated. In one group, the Balistini of authors, the 
ganoid mail is divided by diagonal intersecting lines 
into small rhomboidal discs ; the stout anterior ray of 
the first dorsal is followed by one or two small ones, 
winch act as triggers to fix it in an erect position, and 
when disengaged, allow it to fall back into a gi’oove. 
In the other group (the Monacanthini) the dermal mail 
is in form of small, thickly-set spines, of forms varying 
with the species, and occasionally resembling in fine- 
ness and closeness the pile of velvet. 
The genera are — Py odon ; Melichthys ; Xanthicktkys ; 
Canfhidermis ; Batistes ; Balistapus ; Monacanthus ; Aluterius ; 
and Priacanthus . — (See Kaup, Cat. Brit. AIus.) 
The Pig-faced Trigger-fish or File-fish {Balistea 
capriscus) is a British species, though very seldom cap- 
