199 Ayres on the identity of 
Greatest breadth of the head, six-tenths ; at the pectoral 
fins, nine-twentieths ; at the anus, three-tenths ; at the cardi 
fin, one-tenth. 
Mouth, seven-twentieths of an inch in width, plentifully 
supplied with teeth. In the upper jaw we find the inter- 
maxillaries, which are short, densely crowded with them; 
they are small, very sharp pointed, and sometimes curved. 
In the lower jaw they are also very numerous, the band of 
them becoming broader and more dense toward the front part 
of the jaw. "The vomer is covered with them, as are also the 
upper pharyngeals (forming a rounded patch on each,) and 
the lower pharyngeals, which are longer and narrow. ‘The 
palatine bones and the tongue are smooth. 
The eyes are situated on the top of the head, three-twen- 
tieths of an inch in length, elliptical in form, one-tenth of an 
inch from each other. 
The lateral line arises at the superior angle of the opercu- 
lum, and bending very slightly downward, passes back nearly 
straight to the caudal fin. A row of large and distinct mu- 
cous pores begins at the front of the lower jaw, and passes 
back on each side, as far as to the end of the preoperculum. 
Besides these there are numerous pores, much smaller, scat- 
tered irregularly on the top and sides of the head. 
The nostrils are very difficult to distinguish. When the 
skin is removed, the nasal cavity is found extending almost 
the whole distance from the orbit of the eye to the maxillary 
bone. When the skin, however, is in place, this is not dis 
cernible, and all that we can see is a small aperture, some 
what tubular, apparently single, opening directly into the 
centre of the cavity. Around it are several of the mucous 
pores, one or two appearing to communicate with the cavity; 
but the only proper opening of the nostrils is, I believe, the 
one already mentioned. | 
-.. On each side of the head are two spines. One of them is 
at the inferior angle of the preoperculum ; it is short 
 Stou Mns: flattened vertically, curved — ending 
