22. MONOGRAPH OF THE FRESH WATER Til. 
ought to make the remark that the two posterior rays of the second dorsal have 
been omitted in the engraving, and thus it is not sufficiently near to the base of 
the caudal. The interhemal spines are represented a little too much inclined, 
so that, while the anterior edge of the anal fin is correctly situated, the anterior 
interhemal spine ought to abut against the first caudal vertebra, thus three 
vertebrae more backwards, instead of seeming apparently connected with the three 
pairs of pelvic appendages, the extremities of which alone should abut against the 
anterior interhemal, leaving the latter behind them. The insertion of the ribs is 
more correct than in C. viscosus, although the anterior pair should come higher and 
reach the neural arch. The fins have been cut off from want of space. 
The skull (Plate III, Fig. 22—25) exhibits that remarkable feature in the 
structure of the genus Triglopsis which reminds us of Scizenoids, and consists in 
the presence on the upper surface (Fig. 22), and on the face, of large mucus holes, 
communicating directly with the lateral lme. The general form of the cranial 
box is elliptical, the upper surface smooth in the middle, flat, slightly dipping in 
front. On both sides the mucus channel is open from the paroccipitals to the post- 
frontals, into which it passes, until it meets its fellow of the other side, and takes 
with it a parallel course through the fronto-orbital arcade to the snout. In fact, that 
arcade is entirely transformed into a double channel whose walls are extremly thin and 
semi-transparent. The turbinals are in their respective place on Fig. 22; the nasals 
are not very conspicuous, and are covered in this case by the turbinals, which occupy 
exactly the same position as in Acanthocottus (Fig. 26), where the turbinals are 
also united to the upper part of the snout. The cranial box itself is so thin as to 
shrink in drying when all soft parts, internal and external, are removed. The 
lower surface (Fig. 23) is very smooth; the acoustic capsules are proportionally 
large, although not very conspicuous on the figure, as they had shrunk since they 
were prepared for the purpose of being drawn. In the profile view (Fig. 24) the 
proportional length of the cranial box and the orbito-frontal areade is very obvious; 
the former being shorter and less elevated near the orbit than on the occipital 
region. 
A character belonging to the vomer (12) and which may vanish away during the 
preparative process of the skull, is represented on Plate II, amongst the movable 
bones of the head. This consists in the presence on the anterior and median line 
of that bone, of a narrow elliptical band of teeth similar to those which exist on 
the front of the same bone. 
The premaxillary (22) has the general appearance of an open triangle; its 
ascending branch is shorter than the horizontal one; and terminates in a point, 
behind which there is a flat and much shorter process. The horizontal branch is 
likewise expanded, although the very tip terminates in an acute angle. The mazil- 
lary (21) is an elongated and curved bone, narrow on its middle, provided in front 
with a trifid articulating head, whilst its posterior extremity is flattened, truncated, 
and movable into the membrane which forms the angle of the mouth. 
The palatine (20) is provided posteriorly with a needle-like spine which extends 
backwards in contiguity with the styliform pterygoids. The entopterygoid (23) is 
blade-shaped and has the transparency of the thinnest membrane. The pterygoid 
