231 
The difference in the form of the lingual teeth indicated by 
the authors do not exist in Geotria, and in Mordacla they are 
similar, being, (vhen seen in front, like two small horns, and, 
when sideways, having the appearance of serrated arches. 
N'ota. — I consider as belonging to the Ammoccetes type, or 
larval stage, a singular little Petromyzonid, which was found in 
the Tarra. The body is eel-shaped, naked, cylindrical, and 
elongate, being twenty -three times as long as high ; it is entirely 
divided in annular rings, which appearance seems due to the 
muscular flakes being very visible through the smooth skin. I 
can see no teeth ; the upper lip is flat, and considerably prolon- 
gated over the buccal aperture ; it is truncated in front, and this 
part, seen upperly, is rather bifurcated. The lateral line is well 
marked in all the length of the body ; there is only one dorsal, 
which begins at about two-thirds of the length of the body, and 
is joined with the caudal and the anal ; the latter is considerably 
shorter than the dorsal ; these fins are all equal in their length ; 
no eye visible. The skin of the throat is rather extensible ; the 
prolongation of the upper lip over the lower is equal to the 
height of the body ; the tail is pointed. 
The colour is of a light green, with the belly white ; on the 
back extends a narrow longitudinal line; the head and throat 
are pink, and the fins of the same colour. Total length, four 
and three-eighth inches. 
I should have thought this might be the first state of Geotria, 
but -we have just seen that I had a still smaller specimen of this, 
which has entirely the form of the adult. In this state of things, 
I propose giving provisionally to this the name of Yarra 
Singularis. 
In a dried state, the prolongated part of the head is apt to 
bend upwards, which gives the fish rather the appearance of a 
Syngnathus. The branchial apparatus are visible ; the body is 
remarkably soft, which makes it very difficult to examine it ; no 
barbels round the mouth. 
It was found in Captain Sinnot’s dock, on the lower Tarra, in 
brackish water. 
