PLATE LIY. 
jumble two remote teeth, and have been described as such by Bloch, 
in speaking of the anterior circle of them ; but there is no incision or 
separation of any kind between them to constitute two teeth. On 
each side contiguous to this bony process, but still distinct, is a tooth 
with a double fang ; the process in the center, and double tooth on 
each side, forming together the first principal series of the teeth. 
The next behind are two trifurcated teeth, not extending, like the 
preceding, entirely across the roof of the mouth, but only placed 
one on each side of it. 'I he third, or posterior series, contain in 
the center seven distinct teeth rising from a single bony process, the 
exterior ones on each side from the central tooth becoming gradually 
larp-er and longer. At each end of this series is a small detached tooth 
with a double fang. Beside these, there are in the anterior part of the 
mouth, in front of the bifurcated process mentioned in the first series, 
five or six teeth of a middle size, disposed in an irregular manner. 
The outer border of the mouth has a number of other teeth that are 
very minute, but still perceptible to the touch when the finger is 
drawn over them. 
The only species of this genus described by writers as inhabitants 
of this country, are marinus, fluviatilis, and branchialis. The kind 
we are now speaking of cannot readily be confounded with the two 
others. Marinus in a young state, is marked and spotted very dis- 
tinctly : fluviatilis, it should be observed, is likewise found occasion- 
ally variegated with dusky marks more or less distinct, but it is uni- 
formly distinguished by the connection between the second dorsal fin, 
and that of the tail, the second dorsal fin in P . Marinus being distinct. 
The species branchialis is known by the linear form of this fin, 
the annulated body, and the mouth being destitute of teeth, a cir- 
cumstance, the latter, that has escaped the observation of Mr. Pennant, 
E 3 
