— 133 — 



whicli lodges, as in Scorpaena, a gristly tapering rod-like structure which forms the core of the mandi- 

 bular labial fold of the fish. The pointed anterior limb of the articular is strongly convex externally 

 and concave internally, and lodges, in its concave internal surface, the rod-like Meckel's cartilage. 

 Posterior to the hind end of Meckel's cartilage the conformation of the rod is continued a short 

 distance by a rounded ridge of bone. There is a short, stout, sharply-pointed coronoid process. The 

 hind edge of the articular facet for the quadrate projects dorso-posteriorly as a stout process which 

 has a sliding articulation on the ventro-posterior surface of the posterior process of the quadrate, 

 as in Scorpaena. The angular is a small bit of bone that caps the hind end of the articular and gives 

 Insertion to the strong mandibulo-interopercular ligament. The articular and dentary are both 

 traversed by the mandibular latero-sensory canal, and lodge, respectively, one and four organs of 

 the line. 



4. MUSCLES. 



The adductor mandibulae niuscle of Trigla has anterior and posterior divisions, instead of, as 

 in Scorpaena, superficial and deeper ones. The anterior division forms the anterior third or quarter 

 of the entire muscle and has its origin from a tendinous band that extends along its own dorsal edge 

 and then backward along the dorsal edge of the posterior division of the muscle, to have its origin 

 on the tendinous tissue that forms the anterior edge of the levator arcus palatini. This anterior 

 division of the adductor has its Insertion wholly on a tendinous fascia that forms on its internal surface 

 and that terminates anteriorly in two tendons; a stout tendon inserted on the hind end of the liga- 

 mentary process of the maxillary, and a less important one inserted on the dorsal surface of the 

 same bone. 



The large posterior division of the adductor is partly separated into two portions by the ramus 

 mandibularis trigemini, that nerve traversing the muscle from its inner surface and issuing on its 

 outer surface close to its ventral edge. That part of the muscle that lies anterior to the nerve has its 

 origin on the tendinous band that extends along the dorsal edge of the entire muscle, and that gives 

 origin also to the anterior division of the muscle. It is inserted in part on the tissues that extend 

 from the palato-quadrate apparatus to the maxillary, partly on a tendon that joins the tendon A^ A3, 

 described below, and partly on a tendon that runs forward and has its Insertion on the dorsal surface 

 of the maxillary. This part of this division of the muscle, and the anterior division of the entire 

 muscle, thus together correspond approximately to the superficial portion, Aj, of the muscle of Scor- 

 paena. That part of the muscle of Trigla that lies posterior to the mandibularis trigeminus then 

 corresponds to the muscle A2A3 of Scorpaena, and, like that muscle, it arises from the hyomandibular, 

 the preopercular and the outer surface of the palato-quadrate arch, and has its Insertion on a tendon 

 that may be called tendon AjA^. This tendon is double, having anterior and posterior portions. 

 The anterior portion separates into two parts one of which is continuous with a fascia that forms on 

 the inner surface of A,,^, the other having its Insertion on the internal surface of the articular ventral 

 to the hind end of Meckel's cartilage. The posterior portion of the tendon A.Aj runs downward 

 along the hind edge of A^^ and has its Insertion on the inner surface of the articular dorsal to the hind 

 end of Meckel's cartilage. There is, in Trigla, no tendon running backward, as in Scorpaena, from 

 the tendon A2A3 to the inner surface of the quadrate. 



The maxillo-mandibular ligament is as in Scorpaena. 



