Videnskabelige meddelelser

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Videnskabelige meddelelser

294

The ossifications form a perfect network of bone. Round the

pores are found some tooth-like projections which are pointed and

have a cavity just like the pulp-cavity found in genuine teeth The

projections are amazingly like teeth and especially like those which

are covering the gill-arches, but the enamel-tip, which is easily

to be seen on the genuine teeth (including those on the gill-

arches) is very indistinct here. I feel convinced however that it

is really present.

On the external surface of the hemibranch the ossifications do

not form a connected whole, but when treated with 'Eau de Ja-

velle' several long rods will be left, belonging by twos to the

edge of each branchial lamella.

On the edge of the pores, which are oblong, the same tooth-

like formations are found.

By this arrangement a great rigidity of the gill is obtained.

When dried, it will keep its shape!

I must mention, that the „pseu dobra nch" in Xiphias is well

developed and has the same structure as the following hemibranchs:

connections. pores, ossifications etc.

I had at my disposal some young stages of Xiphias, I exam-

ined their gills and found them quite as in other Teleosts. They

were in no respect aberrant. Even a specimen 190 mm long had

the structure of common gills. The next specimen was 27 inches.

Here I found rather perfectly developed connections on the inner

side of the hemibranch. Ossifications existed, but did not cover

the whole surface of the gill ; especially the distal ends of the

lamellae were free. I shall mention that this has been correctly

stated by Lutken*^).

The gills in the young Xiphias are very like the gills in Acan-

thocyhium, which I shall mention below.

In Histiophorus ghidiiis, of which species a rather young spec-

imen was at my disposal the lamellae were connected, but only

towards the gill arch. Ossifications were only found on the inner

surface of hemibranch.

Finally I shall tell about Acanthocijbiiim, a large pelagic scom-

beroid. As in swordfishes the gills are reticulated, but not as per-

fectly as in the adult Xiphias much more like the young Xiphias

or //istiophorns. On the outer side of the hemibranch the con-

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