— 155 — 



sitrface of the proximal end of the ceratohyal, noar the point wherc that bone articulates with tho 

 interhyal; the attachment apparently being to the interhyal as well as to the ceratohyal. Frora 

 the dorso-posterior end of the interopercular a stout hgament arises, and running dorsally, parallel 

 to and immediately posterior to the interhyal, is inserted on the inner surface of the preopercular. 



The MAXDIBLE is strongly curved at its anterior end, to meet, in the middle hne, its fellow 

 of the opposite side. Its middle point lies considerably posterior to the corresponding point of the 

 Upper jaw, and the dentary, like the maxillary, the premaxillary, and the vomer is wholly without 

 teeth. The articular has a pointed anterior end which projects slightly beyond the hollow of the 

 V between the dorsal and ventral limbs of the dentary, and there lies internal to that bone. Posterior 

 to this point, the ventral edge of this portion of the articular sHghtly overlaps, extcrnally, the dorsal 

 edge of the ventral liaib of the dentary. On the internal surface of the bone, posterior to the hind 

 end of Meckel's cartilage, there is a slight eminence for the Insertion of the tendon of a part of the 

 adductor mandibulae muscle. The bone has a broad thin coronoid process. The angular is almost 

 completely fused with the articular, a sutural line on the externa! surface of the bone alone indicating 

 its presence. The dentary has a long and slender dorsal limb which does not reach, by a considerable 

 interval, the dorsal end of the coronoid process. On the lateral surface of the dorsal edge of the 

 dentary, slightly anterior to the middle of its length, there is a dorso-laterally projecting shelf of bone; 

 and immediately beneath this shelf, on the external surface of the bone, there is the large anterior 

 opening of a short canal which leads backward through the dentary into the ramus of the mandible. 

 This canal transmits a large nerve which goes immediately to the large barbel of the fish, this barbel 

 having its attachment on the outer surface of the dentary in a pit-like depression that lies immediately 

 ventral to the anterior end of the projecting shelf of bone. On the projecting antero-lateral corner 

 of this shelf of bone the mandibular labial fold has its origin. The barbel of Peristedion thus arises 

 from the mandible in the place where the gristle-hke core of the mandibular fold of Scorpaena arises, 

 and, contiguous with it, the mandibular fold has its origin. Whether this means that the core of the 

 mandibular fold of Scorpaena represents, or includes, the barbel of Peristedion, or not, I can not 

 determine. 



The dentary and articular are both traversed by the mandibular latero-sensory canal, the 

 dentary lodging three sense organs of the line, and the articular one organ. 



4. LATERO-SENSORY CANALS. 



The main infraorbital canal has the course already described through the infraorbital bones, 

 the lachrymal lodging four organs of the line, the second infraorbital bone one organ, the third bone 

 two organs, and the fourth and fifth bones one organ each; making nine organs in all in this part 

 of the line, that being the same number as in Trigla. The canal then traverses the postfrontal, in 

 which bone there is a single organ innervated by a branch of the oticus lateralis, and then anastomes 

 with the penultimate tube of the supraorbital canal. The canal then traverses the pterotic, in which 

 bone there is a large pre-preopercular organ innervated by a branch of the oticus lateralis, and in 

 all probability a second and much smaller post-preopercular organ innervated by a branch of the 

 supratemporalis lateraUs vagi. A branch of the latter nerve was found going to the canal in four 

 dif ferent specimens, but the organ, if it exists, is so small that it could not be with certaint}' identified. 

 The canal anastomoses with the dorsal end of the preopercular canal between these two organs. 



