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TRANSACTIONS OF THE AMERICAN PHILOSOPHICAL SOCIETY 



shaping the brain and its responses that they play in existing teleosts. In contrast with 

 the typical isospondyl type, the posterior border of the orbit is so far back that it nearly 

 touches the hyomandibular. "The deep and narrow operculum," writes Woodward (1901, 

 p. 401), "is produced into two short and broad spines at its hinder margin, the upper being 



sm)(. 



■smx' 



Hoplopteryx leioesiensis 



Fig. 110. ' Hoplopteryx lewesiensis. After Smith Woodward. 

 A. Side view of skull. B. Left premaxilla, maxilla and two supramaxillse. 



connected by a strong ridge with the point of suspension." Such then, was the beginning 

 of the "opercular spines" of acanthopts. The interopercular is well developed and has its 

 normal connection below with the posterior projection of the mandible. As to the cranium 

 proper, Tate Regan (1929, p. 319) states that the orbitosphenoid and Y-shaped "basisphe- 

 noid" are retained, two points of inheritance from remote isospondyl ancestors. In the 

 recent Berycidse one or several of the suborbitals emit an internal lamina supporting the 

 eye (Boulenger, I9I0, p. 655). One of these becomes the "suborbital shelf" of the typical 

 acanthopts. 



A careful investigation of the osteology of six genera of recent berycoid fishes was made 

 by Starks (I904i). Among the more constant skull characters of the Berycoidea were the 

 following (p. 602): orbitosphenoids present, head usually with conspicuous mucous cavities, 

 a suborbital shelf present on the suborbital ring; maxillary with a large supplemental bone; ^ 



' Tate Regan (1907a, p. 642) records the presence in Myripristis murdjan of an anterior but vestigial supramaxillar>', 

 homologous with that of the Cretaceous clupeoid Ctenothrissa radians. Starks (1904A, p. 612) also notes the presence of two 

 "supplemental bones" on the maxillary of Holocentrus ascensionis. 



