— 127 — 



entirely upon the condylar process of the exoccipital. This appearance is however deceptive, for, 

 as stated when describing the exoccipital, the postero-mesial and hxrger portion of the base of the arch 

 of the first vertebra rests upon the mesial portion of the dorsal surface of the anterior process of its 

 own centruni. The dorsal arch of the first vertebra is represented by two bones, one on either side, 

 which touch in the mid-dorsal line above the spinal cord but are not there ankylosed with each 

 other. On the lateral surface of each half of the arch, therc is a deep pit which gives insertion to the 

 most anterior rib. Ventral to this pit, the base of the arch is perforated by a foramen which transmits 

 the first spinal nerve. The base of the second arch is similarly pierced by a large foramen which 

 transmits the second spinal nerve; and dorsal to this foramen there is, on the lateral surface of the 

 arch, a large depression which gives insertion to the second rib. The two halves of this arch of the 

 second vertebra meet and ankylose in the mid-dorsal line above the spinal canal, but, like the arch 

 of the first vertebra, this arch does not extend dorsally beyond the point of ankylosis; these two 

 arches being much shorter than the next following ones. 



The POSTERIOR SURFACE OF THE SKULL of Trigla differs somewhat from that of 

 Scorpaena. It slopes rapidly downward nearly to the level of the large foramen magnum, and then 

 curves rather abruptly backward to form the nearly straight and horizontal dorsal edge of that 

 ioramen. Each half of the surface is separated into two portions by the nearly vertical epiotic ridge, 

 and across the dorsal portion of the mesial one of these two portions there is a large and rounded 

 transverse ridge. This ridge is formed entirely by the epiotic and supraoccipital, and apparently 

 corresponds to what I have described, in Scorpaena, as the bind edge of the primary skull; this 

 being more evident in Trigla gurnardus than in Trigla hirundo. Such being the case, the slightly 

 depressed region, on either side, between the transverse ridge and the bind edge of the secondary 

 skull would correspond to the supratemporal pocket of Scorpaena. 



The TEMPORAL FOSSA is relatively small, as compared with Scorpaena. Its posterior 

 opening is bounded mesially and laterally, respectively, by the epiotic ridge and the opisthotic process 

 of the suprascapular, the latter process lying in a nearly vertical longitudinal plane, instead of, as 

 in Scorpaena, in the inclined plane of the lateral surface of the skull. Because of this position of the 

 opisthotic process of the suprascapular, there is a large opening leading into the fossa from the lateral 

 surface of the skull. In the mesial wall of the fossa there is a large but low preepiotic fossa, this fossa 

 "being simply a pocket-like diverticulum of the temporal fossa. The roof of the fossa is formed mainly 

 by the suprascapular and lateral extrascapular, but partly also by projecting edges of the epiotic, 

 pterotic and parieto-extrascapular. 



The SUPRAOCCIPITAL has a large postero-ventral limb which forms a large median portion 

 of the posterior surface of the skull. A small median ridge near the dorsal end of this limb of the 

 bone represents the much reduced spina occipitalis. The dorsal limb of the bone is completely covered 

 by the overlying parieto-extrascapulars excepting only a narrow bind edge and a small and variable 

 portion of its dorsal surface which lies slightly anterior to that hind edge. The anterior edge of this 

 limb of the bone bounds and is continuous with the hind edge of the post-epiphysial cartilage, its 

 lateral edges bounding, on either side, the posterior portion of the lateral cranial fontanelle. 



The EPIOTIC has a stout suprascapular process, this process and also the dorsal surface 

 of the bone itself, being entirely covered, dorsally, by overlying portions of the suprascapular and 

 parieto-extrascapular; the epiotic thus being whoUy excluded from the dorsal surface of the skull. 



