OF THE MARSIPOBRANCH FISHES. 
385 
To me they are part of the skeleton, and therefore come into my description. The 
eye-balls are extremely small, and inconspicuous (Plate 13, fig. 1, e., II.). The auditory 
capsules are very small, but not so small by far as the eye-balls ; they are kidney¬ 
shaped, and look much larger below than above (Plate 10, figs. 1-3, cm.). Indeed, 
below they are oval in form, with the narrow end in front, and, above, the concavity of 
the inner face, which is largely membranous, gives them their reniform appearance ; 
they are composed of hard cartilage, and look like little light green seeds. They are 
confluent with the basis cranii and head of the hyomandibular cartilage ; I shall show 
this in my account of the sections. 
The nasal capsule of the Myxinoids is a unique structure; it is composed of the 
true olfactory organ and the vestibular region, which is proboscidiform (Plates 9, 10). 
The proper olfactory organ is covered with a grating of cartilage (na.), whose bars 
run in a longitudinal direction. 
The whole capsule is wider than long—wider than the brain cavity—is gently 
emarginate behind, and apiculate in front. The floor is membranous, and lies over 
the brain cavity behind, and the “ front intertrabecula ” in front. The roof and 
sides are enclosed by the cartilaginous grating, in which there are nine sub-equal bars, 
united fore and aft by a continuous belt of cartilage ; the bars and these interspaces 
are nearly equal. The olfactory nerves enter the membranous cribriform plate by 
five distinct bundles (see in Bdellostoma, Plate 17, fig. 4—an anticipation of the 
Mammalian ethmoid). 
The proboscidiform nasal tube is very exactly like a Mammalian trachea, being 
composed of a series of imperfect cartilaginous rings, of which I find eleven in Myxine, 
the last being apiculated; it projects forwards above the single narial opening ; these 
parts will be better understood when we come to the sections. The upper seven 
barbels or “ nasal palpi ” protect this opening, and the other four the oral opening; 
they each have a delicate cartilaginous axis. This type of skull remained an utter 
enigma to me until lately, even with the great work of Muller before me ; and I am 
not aware that any one, except Professor Huxley, has, of late years, attempted to 
interpret it; nor should I have attempted now, if the task had not been lightened by 
my fellow workers, and if the early stages of the nearest relatives—the Lamprey, and 
the “ Anura ” in their larval stages—had not been mastered. 
Of course, every determination of the nature of parts made now will be subjected to 
a severe and crucial test when the early stages of a true Myxinoid have been worked 
out. For those stages I am anxiously looking ; but, meantime, this initial work will 
be something done ; a little change of nomenclature, if needed afterwards, will be no 
great matter; and it is very important that this scarcely vertebrate type—it has no 
vertebra —should be understood. The number of sections drawn is great, but they were 
all needed to make even the worker himself understand what lay before his eyes. 
The reader will need to keep the figures of the dissections (Plate 9, figs. 1-3, and 
Plate 10, figs. 1-3 ; Plate 12, figs. 7, 8 ; and Plate 15, fig. 6) before him whilst reading 
