239 
far apart. Mouth very large, surrounded with rather large, trans- 
verse, torn leaves. 
This genus chiefly differs from Velasia in the rudimentary state 
of the lower internal tooth, in the form of the labial teeth, in the 
large size of the oral disk, and the extraordinary development of the 
throat-pouch, which is found in a rudimentary state in the Petro- 
myzon marinus. ‘This development of the pouch is perhaps to adapt 
the animal to the long drought of the Australian rivers. 
1. Gzorria austRALIs. Poucuep Lamprey. (Pisces, Pl. V.) 
Hab, South Australia. Fresh water. 
4. VELASIA. (Pisces, Pl. IV. fig. 4.) 
Upper internal teeth large, transverse, crescent-like, divided into 
four flat, elongated lobes ; the outer lobes largest. The lower inter- 
nal teeth large, transverse, crescent-like, convex, denticulated on the 
edge. The labial teeth very numerous, truncated, in crowded, arched 
series, diverging from the throat; the inner ones large, and gra- 
dually diminishing in size to the edge. Tongue with two very large, 
long, curved teeth, with a triangular plate beneath at their base. 
Dorsal fins two, far apart. Mouth moderate, edged with transverse 
foliations. 
1. VELASIA CHILENSIS. CHILIAN LAMPERN. 
Hab. Chili. In fresh water. 
5. CARAGOLA. (Pisces, Pl. IV. fig. 5.) 
Upper inner teeth two, large, separate, lateral, submarginal, each 
with three acute tubercles. Lower inner teeth large, crescent-shaped, 
nine-lobed ; the central and two lateral lobes on each side larger. 
The labial teeth in a subcircular, submarginal series, large, trans- 
verse, band-like, with three or four tubercles. Tongue with two flat- 
tened teeth, and a triangular, transverse plate below, with an acute 
process between the teeth on the upper edge. Dorsal fins two, far 
apart. 
1. Caracoua Lapicipa. CARAGOL. 
Hab. West Coast of America. 
6. MORDACIA. (Pisces, Pl. IV. fig. 6.) 
Upper inner teeth two, separate, lateral, subtrigonal, each with 
three tubercles. The lower niné conical, acute, in an arched series ; 
the five central smaller. Labial teeth small, conical, in a single, cir- 
cular, submarginal series, with a single, additional, odd tooth in the 
centre above. Tongue with two conical, arched teeth. (Rich. Voy. 
Erebus & Terror, t. 38.) 
Petromyzon, sp., Rich. Voy. Erebus & Terror, t. 38, 1845. 
