NATURAL SCIENCES OF PHILADELPHIA. 
223 
Ichthyological Notices. 
BY CHARLES GIRARDj M. D. 
I. 
Those interested in the study of American animals, and of fishes in particular, 
will hear with interest, of the discovery recently made, of a representative of 
the Myxinoid family on the north-eastern coast of this continent. It belongs 
to the genus 3Iyxine^ so carefully and skilfully investigated by Joh. Miiller. 
It is the more interesting to comparative anatomists, as it typifies the lowest 
grade of the vertebrated plan of structure. The species which we allude to 
closely resembles the European one, 31. glutinosa; like it, it is an inhabitant of 
a rather high latitude, and its habits or mode of living are quite as little under- 
stood. The only specimens that were ever found were collected by my friend, 
W. Stimpson, who gave most of his specimens to Prof. Agassiz, reserving but 
one, which he deposited in the Museum of the Smithsonian Institution. 
The latter specimen is eleven inches and a half long : the thoracic region 
alone is subcylindrical ; the abdominal and caudal regions being quite com- 
pressed and somewhat tapering. The dorsal fin begins somewhat posteriorly 
to the branchial apertures as a mere fold of the skin, increasing very slightly 
in elevation towards the spear-shaped tail, being highest posterior to the vent. 
The latter, in the form of an elongated split, is situated nearly an inch and a 
half from the tip of the tail where the anal fin meets with the dorsal, of which 
it has both the aspect and development. A membranous fold or abdominal fin, 
a good deal more developed than the dorsal one just alluded to, may be observed 
all along the abdominal region, from the vent to the branchial apertures, being 
continuous with the anal fin, properly so called, the vent itself not affecting 
materially its continuity, since it is partly situated between a double fold at 
the origin of the anal fin. As regards the branchial apertures themselves, the 
left one is larger than the right, which is placed somewhat in advance and side- 
ways of the left; they are situated about three inches from the apex of the 
snout. The double series of abdominal mucous pores (one on either side), are 
conspicuous upon the removal of the slimy investment; the pores being about 
an eighth of an inch apart. The head is small, continuous with the body ; its 
anterior aspect is shelving inwardly downwards, the snout being subconical, at 
the apex of which may be observed four subequal tentacles closely grouped 
together, directed upwards and inserted, two on either side, upon the very edge 
of the spiracle which they seem to protect, together with a small flap at its 
posterior margin. The buccal aperture is anterior, below the declivity of the 
snout; it is divided into two parts by a lateral convoluted lip. the upper part 
being subtriangular or subcordiform, the lower part transverse and elongated ; 
its lower periphery is rumpled. The third pair of tentacles is the largest of all, 
and inserted, one on either side, near the upper and outer edge of the convoluted 
lateral lip just alluded to. It hangs downwards like the fourth pair, which is 
the smallest and rather inconspicuous, inserted near the inner and lower edge 
of the same convoluted lip, over the lovrer part of the buccal aperture. Thus 
the eight tentacles constitute four pairs : two rostral pairs presiding over the 
spiracle ; and two buccal pairs presiding over the mouth, one at the upper part, 
the other at the lower. The palatine tooth is slender and elongated. The four 
rows of lingual teeth are composed each of seven sublanceolated and acute 
teeth, much larger in the interior than in the posterior rows. They are very 
crowded and inclined backwards or rather inwards ; the anterior row over- 
lapping the base of the posterior one. 
The color is of a uniform reddish brown or chestnut tint, somewhat lighter 
beneath than above. The membranous fold along the abdomen being whitish. 
The head and anterior aspect of the snout, tentacles and mouth, are whitish 
also. 
From the foregoing remarks it is easy to perceive that we have on the Ameri- 
1858.] 
