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IX. On the Skeleton of the Marsipobranch Fishes. —Part I. The Myxinoicls (Myxine, 
and Bdellostoma). 
By William Kitchen Parker, F.R.S. 
Received December 14, 1882 —Read January 11, 1883. 
[Plates 8-17.] 
Introduction. 
At present, almost nothing is known of the development of these remarkable Fishes, 
but their structure in the adult state is of great interest; and as the other related 
type—the Lamprey—has received great attention lately in most of its stages, I have 
thought that it would be profitable to anatomists to have a detailed account of the 
structure of the skeleton in these lower, and less known types. 
The late Professor Johann Muller left us his inestimable account of the anatomy 
of Bdellostoma, with excellent figures of the skeletal parts; but of Myxine he gave 
very few illustrations. Moreover, the absolutely accurate figures of the skull of 
Bdellostoma are small and uncoloured ; they fail to show the various kinds of cartilage 
of which it is composed, and as this skull is so extremely unlike that of any other 
known vertebrate, except that of the Hag [Myxine), I venture to give my own (new) 
illustrations on a larger scale and coloured. My figures of the skeletal parts of Myxine 
will be, I believe, almost entirely new to science; and, moreover, the time seems to 
have arrived in which some interpretation of these low generalised skulls may be 
attempted. 
This will be done by the help of what we have lately been learning of the develop¬ 
ment of the skeleton of the nearest relative of the Myxinoid—the Lamprey,—the 
subject of Part II. This attempt to explain the Myxinoid type of skull and skeleton 
generally—nearly all the cartilage in these fishes is cephalic —has been done by the 
help of our growing knowledge of the Lamprey, and also by comparison with what 
the writer has traced out in the early conditions of the skull in various types of 
Ichthyopsida, especially in the larva of Lepidosteus, and of a large number of Tadpoles 
of the Amphibia Anura. 
The light thrown upon the Myxinoid cranio-facial apparatus by the early chondro- 
cranium of other and much higher kinds of Ichthyopsida, is much greater than 
might have been expected, for these show, now here, now there, very remarkable 
MDCCCLXXXIII. 3 c 
