FISHES OF THE GENUS ACENTROPHORUS. 



23 



at least, but their connexion with the parasphenoid is not clearly 

 seen. Below the parasphenoid are the crushed remains of the 

 palatal bones, of which it can only be said that a thickened lower 

 border represents the palato^pterygoid bar, and that the shape 

 of the metapterygoid and quadrate can sometimes be roughly 

 made out. The metapterygoid has a central, upwardly directed 

 process (as in Lepidotus, Amia, etc.) for articulation with the otic 

 region of the brain-case. Traquair stated that " a well-marked 

 quadrate is distinct enough," but if he was not mistaken he must 

 have seen some exceptional specimens. A symplectic with a rod- 

 like stiffening lies just inside the lower end of the preoperculum, 



Text- figure 2, 





D E 



Outlines of scales of Acenfrojahortis seen from the inside ; about twice natural size. 

 All the figures except F include scales of the lateral line. A-D. Acentrophorus 

 varians : A, anterior scales (ll.Q. sixth lateral line-scale) ; B, half-way between 

 occiput and dorsal fin ; C, between dorsal and anal fins ; D, last scales of 

 lateral line, with others above and below. E. A. alius, scales above anal fin 

 {na., remains of neural arches and spines). F. A. glaphynis, scales below 

 lateral line between pelvic and anal fins. 



its anterior end overlying the quadrate. Projecting from under 

 the upper end of the preoperculum some part of the hyomandi- 

 bular is often seen ; it is well ossified, and in shape closely 

 resembles the hyomandibular of Lepidotus. All these bones, in 

 so far as they can be made out, are shown in text-fig. 11. Of 

 the hyoid appa.ratus, the anterior part of the ceratohyal and the 

 small hypohyal are frequently shown. The ceratohyal is deep, 

 especially at its fore end ; the hypohyal is knobbed and rather 

 strongly ossified. In one small specimen of A. i-^arians from the 

 Kirk by collection the opei'culars are somewhat displaced, and in 

 the gap thus left three delicate branchial arches are seen. 



The membrane bones forming the exterior of the skull are 



