256 BE. W. G. RIDEWOOD ON THE 



Hyopalatine Series (fig. 5). — The hyomandibular articulates 

 Avith the cranium by a single head, broad autero-posteriorly. Its 

 anterior edge is continued down to meet the upper part of the 

 entopterygoid, and the lateral process of the parasphenoid lies 

 just below and behind the junction. There is here a definite 

 articulation between the parasphenoid and tlie hyopalatine arch, 

 permitting a certain amount of lateral play to the latter, but 

 preventing any antero-posterior movement. The process of the 

 parasphenoid is so firmly fixed between the hyomandibular above 

 and the entopterygoid below, that it is not easy to remove the 

 hyopalatine arch from the rest of the skull without fracturing 

 one or other of these bones. The metapterygoid just fails to 

 reach the articulation. 



A flat lamina of the inner part of the symplectic spreads 

 forward over the metapterygoid and quadrate. There is no 

 separate palatine bone ; the palatine cartilage is unossified, and 

 the ectosteal palatine is indistinguishably fused with the ecto- 

 pterygoid. The palatine cartilage is connected with the ethmoid 

 region of the cranium by a single terminal head, but the con- 

 nection is of a ligamentous, rather than of a synovial character. 

 Crowded teeth occur on the ectopterygoid and palatine. The 

 entopterygoid sends forward a slender process which nearly 

 reaches the front of the palatine ; it bears numerous crowded 

 teeth over nearly the whole of its buccal surface, the largest 

 teeth being those nearest the median plane of the head. I 

 cannot agree with Bridge (Z. c. p. 305) in his contention that by 

 means of the parasphenoidal articulation of Osteoglossum the 

 teeth along the mesial edge« of the two entopterygoids are 

 enabled to grip food-material as by the action of right and left 

 jaws, working inwards and outwards. The teeth in question are 

 certainly obliquely set, as he states, but their points are directed 

 vertically downwards. There can be no question that these teeth 

 act in a vertical direction, and are opposed to the lingual teeth 

 borne upon the bone that covers the glossohyal cartilage and the 

 basibranchials. 



Opercular Series (figs. 4 and 5). — The opercular bone is large 

 and nearly semicircular in outline. The subopercular is small 

 and is sculptured in its posterior part only. The number of 

 branchiostegal rays of Osteoglossum LeicJiardti is stated by 

 Boulenger {I. c. p. 515) to be 15-17. In the specimen now 



