— 125 — 



and first four external levators of the branchial arches, as in Scorpaena. Between the thick dorsal 

 end of this brace-like process and the adjoining portion of the sphenotic, there is a deep socket-like 

 articular facet for the anterior articular head of the hyomandibuhir. Slightly posterior to this facet, 

 on the hiteral surface of the pterotic, is the oval and shallower facet for the posterior articular head 

 of the hyomandibular. Immediately dorsal to the line between these two articular facets, there is 

 a pit-like depression on the adjoining edges of the pterotic and sphenotic, the depression lying imme- 

 diately beneath the postfrontal. It is the dilatator fossa, the dilatator operculi arising partly in this 

 fossa and partly on the external surface of the dorsal end of the hyomandibular, as in Scorpaena. 

 Immediately anterior to the dilatator fossa, and slightly dorsal to the anterior articular facet for the 

 hyomandibular, on the slightly concave dorso-lateral corner of the sphenotic, the levator arcus palatini 

 has its origin. A canal for the ramus oticus traverses the sphenotic, entering that bone on its 

 orbital surface. 



At about the middle of the lateral surface of the brain case, and near the hind edge of the 

 proötic, there is a small foramen which transmits the root of the nervus glossopharyngeus. Dorsal 

 to the hne between this foramen and the vagus foramen there is a triangulär subtemporal depression 

 which, as in Scorpaena, gives origin to the adductor hyomandibularis and adductor operculi, and also, 

 immediately posterior to the latter muscle, to the external levators of the fourth and fifth branchial 

 arches. The levator operculi has its origin along the dorsal edge of the lateral surface of the skull, 

 as in Scorpaena. 



The PTEROTIC contains two latero-sensory organs innervated by the oticus lateralis, and 

 one post-preopercular organ innervated by the supratemporal brauch of the lineae lateralis vagi. 

 The two Organs innervated by the oticus were found in both of the two specimens examined, one being 

 an adult Trigla and the other a small Lepidotrigla. These two organs lie relatively close together 

 and there is no indication whatever of a primary tube between them. They accordingly quite probably 

 represent the two independent otico-squamosal organs of Amia, here in process of concentration into a 

 Single organ, exactly as already set forth for the fourth and fifth supraorbital organs of this fish, of 

 Sebastes and of Scorpaena. Otherwise the pterotic of Trigla offers no apparent difference from the 

 bone in Scorpaena, excepting in that its posterior process is less extensive. The dorsal portion of the 

 hind edge of the lateral surface of the brain case projects latero-posteriorly as a tall, thin ridge of bone, 

 but this ridge is formed mainly by portions of the exoccipital and opisthotic, its dorsal edge only being 

 formed by the posterior process of the pterotic. 



The OPISTHOTIC forms an actual part of the bounding wall of the posterior semicircular 

 canal, a part öf that part of the pterotic region of the chondrocranium that, in Scorpaena, bounds 

 this canal having been suppressed in Trigla, and a large opening, leading directly into the canal, being 

 exposed when the opisthotic is removed. The opisthotic does not, however, seem to have anywhere 

 acquired primary relations to the skull, the underlying cartilage apparently having simply been 

 resorbed. 



The EXOCCIPITAL is perforated by two foramina, one for the vagus and the other for the 

 occipital nerves, these two foramina being separated by the base of the condylar process that gives 

 articulation to the anterior articular process of the first vertebra. In Scorpaena both of these foramina 

 lie antero-lateral to the base of the condylar process, separated by a slight ridge which is a ventral 

 Prolongation of the postoro-Iateral angle of the skull. Dorsal to the foramen for the occipital nerves 



