86 YYEALDEN AND PURBECK FOSSIL FISHES. 



or punctations. Tlie upper circumorbitals, as usual in Gaturus, seem to have been 

 irregularly subdivided. The mandibular suspensorium is inclined backwards, and 

 the stout hyomandibular is visible beneath the cheek-plates. The maxilla (ma?.) is 

 smooth, with slight longitudinal grooving, and its hinder end is overlapped by a 

 long and narrow supramaxilla (smx.). It exhibits its usual slight sinuosity, and is 

 a little deepened where its oral border curves downwards behind. The relatively 

 large teeth with their nearly square base fused to the bone, their extensive inner 

 cavity, and their slender incurved apical half, with a triangular tip of ganodentine, 

 are well seen : they become especially small and slender behind. The extended 

 premaxilla (pmx.), with five or six tooth-sockets, seems to have borne rather larger 

 teeth. The mandible, shown both in the type specimen and in a smaller specimen 

 (PI. XIX, fig. 2), displays its characteristic upturned pointed symphysial end, and 

 rises behind into a short coronoid region, in which the ordinary separate coronoid 

 bone (co.) and small angular bone (ag.) can be distinguished. The dentary (J.) is a 

 nearly smooth bone, punctate in part and marked by a row of pits along the course 

 of the slime-canal ; the angular bone is strongly punctate. The teeth resemble 

 those of the maxilla, but are somewhat larger. The teeth of both jaws often 

 exhibit a median indent on their outer face at the base ; and the bone round 

 their insertion is sometimes marked with very fine short radiating grooves or 

 crimpings. 



A dentary bone in the Sedgwick Museum, Cambridge, is one-third larger than 

 that of the type specimen ; and part of another dentary in the Beckles Collection 

 (B.M. no. P. 6388) is equally large. 



The remains of the opercular bones in the type specimen are smooth, apart 

 from fine punctations ; and the clavicle (cl.) is only marked by a few vertical lines 

 within its overlapped margin. Ossified hypocentra (hy.) are seen in the anterior 

 part of the trunk, besides neural arches and ribs, partly obscured by the usual thin 

 scales. The base of the pectoral fin (pet.) shows the stoutness of its smooth, closely 

 adpressed rays. 



Horizon and Locality. — Middle Purbeck Beds : Swanage, Dorset. 



3. Caturus tenuidens, A. S. Woodward. Plate XIX, figs. 3, 4. 



1895. Caturus tenuidens, A. S. "Woodward, Geol. Mag. [4], vol. ii, p. 151, pi. vii, figs. 7, 8. 



Type. — Mandibular ramus ; British Museum. 



Specific Characters. — Teeth very slender, usually incurved at the apex, less 

 swollen at the base than in the type species and in G. purbeckensis, usually well- 

 spaced in the jaw. Dentary bone almost smooth, curved a little upwards at its 

 pointed symphysial end ; height of teeth in middle of dentary series much less than 

 the depth of the bone at their insertion. 



* 



