PERCOIDEiE. 21 



The Head measures a little less than one-third of the total length, including the caudal 

 tin, and is twice the length of the tail, from the anal to the end of the scales. Eyes large and 

 rather prominent, placed about a diameter of their orbits apart from each other, the same 

 distance from the tip of the upper jaw, and also from the articulation of the lower one, and 

 two diameters from the tip of the gill-covers *. The infra-orbltar bones form an irregular, 

 uneven plate before the orbit, but merely a narrow margin beneath it. The cheeks are rather 

 large, and are entirely covered with scales. The snout is short and obtuse. The mouth, 

 when closed, descends obliquely towards the articulation of the lower jaw, which is opposite 

 to the centre of the orbit : its orifice commences in the axis of the pectoral fins, and is about 

 twice as much below the ridge of the back, as it is above the rim of the belly. The inter- 

 maxillaries form the whole upper margin of the mouth. The labials project more than half 

 their length from under the anterior infra-orbitar plate, are strong, become gradually wider 

 towards their lower ends, which are truncated and cover the corners of the mouth. The 

 under jaw has a little depth vertically at its extremity, forming a kind of chin when the mouth 

 is closed : there are five orifices in each limb of the bone communicating with an internal 

 canal, two of the holes on each side of the chin being connected with pores in the recent 

 specimen. The two jaws, the snout anterior to the centre of the orbits, the infra-orbitar 

 bones, the labials, preoperculum, some ridges and margins of the other opercular pieces, and 

 the branchiostegous membrane, are covered with smooth skin, but the rest of the head is 

 scaly. 



Teeth small, short, not very acute, but numerous and crowded like velvet pile (en velours 

 ras) into stripes or plates, which cover the edges of the jaws and chevron of the vomer to the 

 breadth of a line. The outer edges of the palate-bones are covered by a narrower band of 

 rather shorter teeth, and there is an oval patch of them, a quarter of an inch long, near the 

 middles of these bones. Our specimen has lost the tongue. 



Gill-covers. — Preoperculum having its upper limb ascending vertically, nearly at a right 

 angle to the lower one, which is shorter and wider. The anterior edge of the bone is elevated, 

 its surface is uneven, and its inferior margin is very regularly and distinctly denticulated with 

 fine grooves running upwards from between the teeth. In the recent specimen these are con- 

 cealed by the smooth skin. The interoperculum has a row of scales along its upper border, 

 which are partially covered by the serrated edge of the preoperculum : the under part of the 

 bone, exceeding the scales in breadth, is smooth with an even edge. The suboperculum is 

 very small and of a triangular form : its upper angle is covered by two small scales ; its lower 

 border is smooth. The operculum, forming by far the largest part of the gill-cover, is also 

 triangular, its posterior apex terminating in two thin lobes or plates separated by an acute 

 notch : the upper of these plates is truncated ; the lower one projects farther, is more acute, 

 and is slightly jagged, or obscurely crenated on its under edge — these plates are edged with a 

 membrane which lengthens them out and alters their form a little, at the same time conceal- 

 ing the crenatures. The anterior border of the operculum is raised into an even smooth ridge, 

 which has a row of three scales between it and the slightly-overlying edge of the preoperculum. 



* The eye is considerably larger than in the Pomotis described in a subsequent page. 



