FOSSIL AND RECENT 159 



hm 



pr m 



Fig. 79. Albula vulpes (Linnaeus). Hyopalatine series of left side in lateral view. 

 Composite of several B.M.N.H. specimens. 



the development of a ridge running antero-ventrally across the otic bulla from beneath 

 the hyomandibular foramen, providing an anchorage point for branchial muscula- 

 ture ; and the deep excavation at the base of the ascending process of the para- 

 sphenoid. This excavation is seen in other albuloid fishes although its significance 

 is by no means clear. Postero-dorsally to the opening for the hyomandibular trunk 

 there is often seen in large specimens (e.g. B.M.N.H. 83. 12. 15. 106) a foramen which 

 leads directly to the cranial cavity. Since this foramen is not a constant feature 

 it cannot be of any great significance. 



Within the orbit Albula shows a completely ossified interorbital septum which is 

 sutured with a greatly expanded basisphenoid stem. Anteriorly the lateral eth- 

 moid is large and stout, totally unlike that element in pterothrissids. Ventrally 

 the lateral ethmoid is sutured with a thin lateral wing of the parasphenoid. The 

 lateral ethmoid also bears a rounded articulatory area which articulates with the 

 posterior process of the palatine. 



The parasphenoid is wide throughout much of its length and bears many hemi- 

 spherical teeth. Each parasphenoid tooth is smooth. The tooth size varies con- 

 siderably throughout the toothed area but generally those teeth towards the rear 

 of the patch are substantially smaller than those anteriorly. The vomer bears 

 three or four rows of needle-like teeth which are inserted on a short pedicel. 



Hyopalatine bones. The hyopalatine series is very much like that of Pterothrissus. 

 The series is long and shallow ; the hyomandibular slopes forward and between it 

 and the metapterygoid there is a large foramen ; the quadrate shows a posterior 

 spinous process and the ventral margin lies almost horizontally ; the symplectic is 

 flattened and lies against both the metapterygoid and quadrate ; the autopalatine 

 is long and overlies much of the ectopterygoid. 



The palatine remains largely cartilaginous, except in larger individuals. Two 

 processes of the palatine begin to ossify early ; anteriorly there is a rounded ethmoid 



