1904,] OSTEOLOGY OF THE ELOPID^ AXD ALB ULID.E, 51 



from the ectosteal articular, and the articular facet for the head 

 of the quadrate is formed in its upper part by the endosteal 

 articvtlar, and in its lower part by the combined angular and 

 ectosteal articular. 



Hyopalatins 6eries (text-fig. 17, p. 50). — The hyomandibular arti- 

 culates with the cranium by a single broad head, and its axis slopes 

 downward and forward. Owing to the smallness of the gape the 

 quadrate-articular joint is far in advance of the hyomandibular- 

 cranial articulation, and the symplectic runs nearly horizontally 

 forwards. The palatine cartilage ossifies at its anterior and posteiior 

 ends, but remains unossified for the greater portion of its length. 

 The anterior head articulates with the mesethmoid, the posterior 

 with the prefrontal. The ectosteal palatine is of small extent, and 

 bears crowded, small, long, shai-p teeth. It is united with the 

 anterior of the endosteal palatines, but is remote from the posterior 

 one. The hinder two-thirds of the palatine cartilage, and its 

 posterior ossification, lie in a trough formed by the ectopterygoid 

 and entopter3''goid. The entopteiygoid bears an elongated patch of 

 hemispherical teeth similar to those on the parasphenoid ; the 

 ectopterygoid is toothless, or may bear two or three small teeth in 

 continiiation of the patch of teeth on the palatine. There is a 

 prominent, externally-directed, horizontal process of the ectoptery- 

 goid, which serves to form part of the floor of the orbit. Its outer 

 edge rests against the upper edge of two of the suborbital bones. 



Opercular Series (text-figs. 16 & 17, p. 50). — The subopercular is 

 large. The branchiostegal rays are 15 in number; they all arise 

 from the outer face of the hyoid arch. The first two lie freely 

 in the branchiostegal membrane, the next ten are attached to 

 the posterior two-thirds of the ceratohyal, and the last three are 

 attached to the epihyal. They form a well-graduated series, those 

 in front having the form of slender curved needles, the hinder 

 ones being larger and lamellate. 



Hyohranchial Series (text-fig. 18, p. 52). — The upper and lower 

 hypohyals are equal in size, although in an external view the 

 lower appears to be the larger. The urohyal extends back a little 

 beyond the posterior extremity of the third basibranchial. The 

 gill-rakers are all short and stumpy. The interhyal is ossified. 



There is a conspicuous dentigerous membrane-bone covering 

 the first, second, and thii-d basibranchials and the hinder part of 

 the glossohyal. The teeth are hemispherical, and resemble those 

 of the parasphenoid and entopteiygoid, with which, in fact, they 

 engage. The glossohyal is movable beneath this dentigerous 

 plate, but the basibranchials are not. The body of the glossohyal 

 consists of cartilage in front and cartilage-bone behind, and an 

 edentulous thin membrane-bone covering both. There is a very 

 small dentigerous bone covering that cartilage which represents 

 the fourth and fifth basibranchials ; the teeth of this are small 

 and pointed, like those of the gill-rakers. 



The first pharyngobranchial is perfectly conformable with thg 

 second, and is set in a line with the first epibranchial. A true 

 spicular bone appears to be wanting. The third pharyn^O' 



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