FOSSIL AND RECENT 



117 



suitable specimen of 0. latifrons was available it is not certain if the unusual disposi- 

 tion of the orbital artery is normal for this species or merely an individual variant. 



Within the orbit 0. latifrons differs from the type-species in the membranous inter- 

 orbital septum and the small basisphenoid stem, although, as in 0. lewesiensis, 

 there are two posteriorly directed prongs arising from the posterior margin of the 

 stem. The parasphenoid of 0. latifrons is proportionally wider throughout, par- 

 ticularly beneath the otic region. The parasphenoid tooth patch is as extensive 

 as in the type-species but the teeth are slightly different. The parasphenoid teeth 

 of 0. latifrons are of irregular size and vary in shape from small, villiform teeth to 

 larger hemispherical teeth. The teeth become larger posteriorly and those in the 

 centre are larger than the marginal teeth. 



Hyopalatine bones. The quadrate/mandibular articulation lies beneath the lateral 

 ethmoid, further forward than in the type-species. A distinctive feature of the 

 hyomandibular is the thin bone forming the head ; otherwise there is agreement in 

 form with 0. lewesiensis. The metapterygoid is imperfectly preserved dorsally, 

 but it probably reached the antero-dorsal point of the hyomandibular and resulted 

 in the presence of a hyomandibular-metapterygoid foramen as in albulids and 

 pterothrissids. The lateral surface of the metapterygoid is marked by a prominent 

 ridge, present in other species of Osmeroides, which provided an anchorage for a 

 superficial division of the levator arcus palatini musculature. The quadrate, 

 although of normal shape, is positioned so that the posterior margin lies almost 

 horizontally. There is a considerable gap between the ventral end of the hyomandi- 

 bular and the quadrate. This gap was presumably bridged by the symplectic. 

 The symplectic was not seen but the impressions left upon the quadrate suggest 

 that it was somewhat flattened, as in Albula. The metapterygoid contributes to the 

 symplectic support. The ectopterygoid is almost as wide as the endopterygoid but 



fahm 



20mm 



boc 



Fig. 57. Osmeroides latifrons Woodward. Neurocranium in left lateral view. 



