140 PROF. R. COLLETT ON A [Mar. 2, 
the last is, however, in the uninjured specimen scarcely perceptible 
beyond the common skin which covers the head. 
The length of the head from the end of the lower jaw to the base 
of the spine on the operculum is to the total length as 1 to 2°7, this 
measured to the end of the caudal fin, but only 1:9 in the length 
to the root of the caudal. Thus the head is about the same as the 
rest of the body without the caudal fin. 
The highest part of the skull is indicated by a protuberance at 
the back of the head, probably formed by the point in which the 
os mastoideum (occipit. posterius) adjoins to the shoulder-girdle. 
The mouth is enormously large, with the cleft oblique; the lower 
jaw is slightly longer than the intermaxillary, and has backwards a 
considerable width (or about 7 of its length). 
The length of the jaws is to the total length (to the end of caudal 
fin) as 1 to 2°8-3°0. At the back of the lower jaw there is a spine 
slanting inwards and downwards, the length of which scarcely equals 
the orbital spines. 
The eyes are well developed, although small on the whole; the 
lens is particularly small (about 1 millim.). The diameter of the 
eye is about 2°5 millim. ; it is placed somewhat far forward, or a little 
more than two orbital diameters from the margin of the upper jaw. 
The gill-covers are but incompletely ossified, but their construction 
cannot be properly examined in this single specimen. The operculum 
is present as a long styliform bone, which towards its lowest end sends 
out a backward-directed spine the length of which is 3 millim. 
(which, however, is completely enveloped in the common skin of the 
head). 
tthe preoperculum appears to be unossified. 
The gill-openings are extremely small, and are situated at a 
distance of about half an eye’s diameter below the pectoral fins; they 
form a crescent-formed slit, the height of which is only 2:2 millim. 
The gills are 24 pairs, as the second and third branchial arches 
have a double series, the fourth a uniserial gill. Pseudobranchie 
are wanting. 
The branchial arches are smooth on their inner surface, without 
a trace of protuberance or teeth. 
The branchiostegals appear to be but five in number; and I cannot, 
in this little and frail specimen, discover a sixth, which may possibly 
exist. 
The feeth are placed in a single row in each half jaw, with a 
distinct space between each tooth, and consist of long and slender 
teeth, some of which are very long, while the rest are somewhat 
shorter. They are finely streaked throughout their length, pointed 
like awls, and movable inwards, so that the long front teeth lie 
backwards, the side teeth inwards. 
All of them are covered with a jet-black skin, the extension of 
which cannot with certainty be determined in this specimen ; a few 
of the shorter teeth are still completely covered with it; but the 
points of long teeth have probably always been bare. 
The number of teeth in each half of the jaw is 7-9, to which 
