Videnskabelige meddelelser

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Videnskabelige meddelelser

292

The Lophobranchs are always mentioned because of the peculiar

form and arrangement of the branchial lamellae, but the gills in

Lophobranchs are much more like ordinary gills, than the gills in

Xiphias, Histiophoriis and Acdnthocybiiim. To begin with the

gills in Mola will have to be shortly dealt with

In Mola the branchial lamellae have a rather striking appear-

ance, their edge not being sharp but broad and rounded, thicker

than the median part of the gill-leaf. The edges of the lamellae

are rough to the touch. Alessandrini^) and Liitken') have

dealt with this matter. Liitken says :

„Every

gill consists as

usual of two rows of pointed leaves; each gill-leaf is supported by

a thin bony lamella the edges of which are framed by a thin rough

crust of bone, made of a thick coating of the previous mentioned

asperities or dermal teeth. As this laver covers the free edges of

all the lamellae, the whole gill is consequently covered with it,

and all the gills placed with such crusty or so to say armoured

rough sides against each other or against the no less rough walls

of the branchial cavity."

If treated with 'Eau de Javelle', of such a lamella there will

be left the cartilaginous leaf with its bony sheat. The latter is

fenestrated irregularly. Further the two long fragile crusts, of

which the broader has covered the outer edge of the lamella,

while the narrower has covered the edges of the lamella facing the

gill-arch. If put under the microscope each crust will show a lot

of pointed ossifications with a very broad base. The ossifications,

which are hollow, are basally connected.

The above mentioned structures effect a better support and

protection for the lamellae, than usually in Teleosts.

In the adult Xiphias the gills are most peculiar. The gill-

arches do not as usual carry two rows of free gill-leaves, but two

perforated disks which are rough to the touch.

Cuvier-) says concerning this matter: „L'éspadon {Xiphias

gladius) parait au premier coup-d'æil avoir le double des branchies

des autres poissons — — ."

Strange enough that the famous anatomist has the same opinion

as Aristoteles that Xiphias has eight gills on each side. This

is of cause wrong.

Cuvier & Valenciennes^) have further: „Chaque lame

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