Excerpt from Morphology of the Myxinoidei, Vol. 1: Two Plates

We propose now to discuss the homologies of the head skeleton of Bdellostoma - as abasis for the more general state ment of the homologies between the Cyclostomes and Gnathos tomes. Professor Huxley (1) announced several years ago that There appears to be no sufiicient foundation in the present state of knowledge for regarding the Marsipobranch skull as one which departs in any important respect from the general vertebrate type. A contrary View has more recently been published by Prof. Howes We quote his statement in full for the reason that it represents the generally accepted View as to the position of the Maripobranchii, as shown by a study of their morphology. He says, (p. 141) In view of the admitted importance of that (referring to the relations of the pituitary body) it testifies, to my mind, to an enormity in the gap between the Marsipobranchii and the remaining Vertebrata which even Balfour's conclusion that the former are the remnants of a primitive group and Haeckel's famous aphorism that they are further removed from the fishes than the fishes are from man, insufiiciently expresses. It disposes of the attempts to prove that connecting links be tween the Marsipobranchii and the higher Vertebrata are known to us; and it is, to me, a question as to whether it does not war rant a greater than a class distinction, viz the subdivision of the sub-kingdom Vertebrata into two lesser sub-kingdoms; the one Epz'cram'ata for the reception of the Marsipobranchii alone, the other, Hypocmm'ata for all the higher forms. It is not neces sary to quote from Other authors since these two views represent fairly well the two groups Of anatomistsq - the one of which ha aflirmed that there exists between the Marsipobranchii and re maining Vertebrata so close a relationship that a general homologyof the parts may be established, the other of which maintains that there is no relation between these two groups of animals save that of their common vertebrate ancestry. Naturally, in attempting to solve this problem recourse is first had to the anatomy of the head. No one had previously established clearly the homologies of the cephalic skeleton, though Huxley very suggestively carried through a comparison of the Myxine and Petromyzon skulls with those of the higher vertebrates. He did not, however, work out his views in final shape, nor does his work Show that he even approached a correct solution of the problem. All anatomists, Huxley included, have accepted Johannes Miiller's View concerning the nature of the structure peculiar to the Marsipobranchii, viz: the so - called tongue. And all have apparently overlooked the fact that were this a tongue or tongue-like organ, it would be a great anomaly in ver tebrate anatomy since none Of the fishes, even the higher fishes, possess a tongue or even a tongue-like organ. The homology of this organ with the vertebrate tongue has never been discussed, nor do we know Of any efforts to determine the true nature of this organ. In our efforts to establish the homology of the parts between the Marsipobranchii and the Gnathostomes, we were at once confronted with the so-called tongue, and after a careful in vestigation of the whole subject, we find that by determining the nature of this organ, we have solved the puzzle of Marsipobranch head morphology. Dr. Ayers began this investigation at the Hopkins Seaside Laboratory in the spring of 1892, and continued at the University of Missouri during the years 1896-98, where Mr. Jackson joined him in the work.

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