1904.] OSTEOLOGY OF THE ELOPIl>>E AND ALiiVLlDM.. 39 



dorsal view (jf tlin craiiiiun. 'I'he lateral temporal gi-oove lies over 

 the postfroiita] bone, and is partially roofed over by a laminar 

 extension of the stjuaniosal. 



The subtempoiul fossa, beneath the facet for the reception of 

 the posterior ]ie:xd of the hyomandibular, is deep and extends 

 inwards and upw;irds beneath the floor of the posterior temporal 

 fossa. Its I'oof is formed by the squamosal, its floor and sides by 

 the pro-otic and exoccipital, wliile its internal csecal end is formed 

 by the supraoccipital. Tlie opistliotic is small, and sends a process 

 forwaixl, below the subtempoi-al fossn,, to meet a backwardly 

 directed process of the pro-otic. 



The basisphenoid is of fair size. Its boily is embraced by the 

 alisphenoids and pro-otics, and it has a, vertical descending plate 

 which divides the eye-muscle canal and touches the parasphenoid 

 by its lower edge. An orbitosphenoid of moderate size is present, 

 but the greater part of the interorbital septum is membranous. 



The parnsphenoid, which bears a spearhead -sliaped patch of 

 fine teeth, extends Ijack as far as the occipital :i,i-ticulation, btit 

 does not project beycmd. The eye-muscle canal opens postei-iorly 

 by an apei-ture of moderate size. The vomer has fine teeth, 

 disposed in two patches, right and left. The ethmoid region is 

 very lai-gely cai-tilaginous. The pi-efrontals ai-e purely ectosteal, 

 wliile the mesethmoid is (:]eai-ly of double oi'igin, the upper part 

 (supra-etlimoid of some aiithors) being a membiune-bone, while 

 the low^er pai-t, of diminutive size, is a cartilage-bone, separating 

 without much difficulty from the former, Init firmly united mth 

 the vomer. 



Temporal >Series.- -The supratemporal is a large thin lamina of 

 bone with a sensory canal running along its anterior edge, which 

 edge is in contact with the posterior edge of the parietal and 

 sipxamosal bones. The hinder Ijorder of the supi-atemporal is 

 deepl}' notched, which gives at first sight the impression that the 

 V)one is double. The mesial edge of the supratemporal lies over 

 the suprivoccipital crest, while the lateral edge overlaps the upper 

 part of the opercular bone. The meeting of the two supra- 

 temporals in the middle line of the head is noteworthy, and is 

 reminiscent of Amia. 



The post-temporal has one limb loosely bound by fibrous tissue 

 to the top of the epiotic, and a shorter and moi'e slender limb 

 attached to the back of the opisthotic. The third limb, lying 

 beneath the supratemporal, is very short, and just fails to reach 

 the outer edge of the posterior temporal fossa ; but projecting 

 forward from it is an ossified tendon, which terminates in a kind 

 of brush in the middle of the fossa, as in Albida. 



Circmnorbitcd Series (text-fig. 9, p. 40). — The nasal aperture is 

 surrounded by three bones ; the orbital ring is complete, and 

 consists of seven bones. 



Maxillary Series (text-fig. 9, p. 40),— The gape is large, bounded 

 above by the prema,xilla and maxilla, Ijoth of which bear densely- 

 set minute teeth extending along the whole of their lower borders. 

 There are tw'o surmaxillaiy Ijones. 



