OF THE MARSIPOBRANCH FISHES. 
399 
figures fail to show the involution of cartilage round the anterior canal as seen in 
the sections of these parts in Myxine (Plate 14, fig. 3, au.). The “meatus” are seen 
almost directly from above (fig. 2), and they are margined on their inner edge by 
the parachordals as they pass into the trabeculse (tv., tr.). The proper olfactory 
capsule (Plate 16, figs. 1, 6, net. ; and Plate 17, fig. 1, net.) is only gently modified 
from that of Myxine; its fore margin is partly united with the last ring of the 
outer nasal tube ( e.n.t .). There are only eleven imperfect annuli in Myxine 
(Plate 10, fig. 1 e.n.t.), in this type there are twelve, but these are not quite 
distinct, as in the Hag Fish ; here, the first three are united, and have one small and 
two large fenestrse ; the seventh and eighth are joined in the middle, and the twelfth, 
partially, with the proper capsule (na.). So unlike is the structure of the lips in 
these, to what is seen in any other types, that nothing but re-dissection enabled me 
to understand Muller’s perfectly accurate figures ; especially was this the case in 
the “ barbels.” 
Here (Plate 16, fig. 1 ; and Plate 17, figs. 1-3, n.bb., o.bb.) they are much more modified 
than in Myxine (Plates 9 and 10). The upper pair (1st nasals) are united across the 
mid-line by a strong commissure which passes under the top of the front intertra¬ 
becula ( a.i.tr .), and the second pair (2nd nasals) are attached to the first where they 
pass into the cross band. 
The upper orals (o.bb.) are triradiate, they send an upper curved ray to join the 
two nasal palpi, and from their proper palpal part which grows forwards they send 
backwards a lobe over the 4th (or 2nd oral). This latter cartilage is bent forwards, 
and then sends out three short snags; its upper horn fits into the angle of the 1st 
oral, and its hinder horn turns backwards and downwards, nearly reaching the front of 
the “ supra-lingual ” apparatus. If we turn to the figures of the barbels in their 
undissected state, we shall see reason to believe that they all belong to the upper lip 
(Plate 8, figs. 7-9 ; Plate 13, fig. 7— Myxine; and Plate 15, fig. 5 — Bdellostoma) ; in the 
large kind the 2nd orals are but little produced as barbels, but form an evident fold in 
front of the lower lip. Thus, in the fullest development of a Myxinoid’s mouth there 
is no more promise of what the transformed Lamprey shows in the lower lip than 
in its own larva—the Ammoccete. As Marsipobranchii, the “ Myxinoids ” are more 
specialised, in some important respects, than the “ Petromyzoids;” but as suctorial 
Fishes they are altogether below them, bearing to them a sort of quasi-larval relation. 
Description of a longitudinally vertical section of the head of Bdellostoma. 
In this section (Plate 16, fig. 6) we see many things brought into view which may 
help in the comprehension of this remarkable type of cranio-facial skeleton. Muscular 
segments and their interseptal fibrous tracts are found running over the brain up to 
the nasal sac (na., ol.) ; the brain mass (C.) insensibly passes into the myelon (my.), 
which latter is supported by the large notochord (nc.). This figure shows the vacuoles 
3 f 2 
