229 
by their having preserved their horny coverings. It has no trace 
of the gutteral pouch, and so I believe that this is accidental, or 
rather belongs to a particular state of some specimens, perhaps to 
the old individuals of one sex. The only dental difference between 
Geotria and Mordax seems to be the presence in the latter of the 
two groups of three long teeth in the maxillary. Nothing shows 
better the remarkable knowledge that Dr. Gunther possesses of 
fish than his not having taken the extraordinary gular sac as a 
generic character ; but I cannot consider the specimens which 
do not possess it to be young, as the length of the one I have 
described here is a little more considerable than that of the 
type in the British Museum (twenty inches). 
In the list of the Gliondropterygii of the British Museum it is 
said that the type, which was given to that institution by Mr. 
Pain, was from a river Inkar Pinki, in South Australia, but 
there must be some confusion, as that gentleman tells me that 
he picked it up on the Brighton beach, Hobson’s Bay. 
MOEDACIA. 
Formed by Gray on a Lamprey from Tasmania, which has 
appeared to Dr. Gunther to be similar to one from Chili. There 
is no doubt that the two belong to the same genus, but it is 
very improbable that they should be specifically similar. 
MOEDACIA MOEDAX. 
Petromyzon Mordax, Biohard, Loo. Git., p. 62, pi. 38, fig. 3. 
Mordacia Mordax, Gray, Ohondropteryqii of the Brit. Mus., 
p. 142 
^ — Gunther, Catal., vol. viii., p. 508. 
{The Lamprey?) 
The mouth is elleptical ; the lateral lobes not broad nor fringed ; 
mandibulary lamina not visible externally, but bearing seven to 
nine acute conical cusps, which, when the horny coverings fall, 
have the appearance of tubercles. On the maxillary is, on each 
side, a group of three conical, acute teeth, directed backwards, 
and placed one in front and two behind ; suctatorial teeth form- 
ing a circle round the lips ; they are small, and number at least 
twenty ; behind them is a series of much larger ones, very broad 
at their base, and very acute ; in front, three of them are dis- 
posed in a triangle ; the others emit a sort of transverse ridge 
