n6 



ELOPIFORM FISHES 



pto 



f m 



f uv 



Fig. 56. Osmeroides latifrons Woodward. Neurocranium in posterior view, 

 This and Text-figs. 57 and 58 from B.M.N.H. P. 11 190. 



very large and the ridge which forms the medial margin in all Osmeroides species is 

 particularly well developed here. The intercalar was not seen but the surface mark- 

 ings on the exoccipital and pterotic suggest that it was of limited size (Text-figs. 

 56, 57 and 58). 



The lateral surface of the neurocranium shows a large otic bulla and a deep sub- 

 temporal fossa. Both of these structures are developed to a greater degree than in 

 the type-species. Indeed, the subtemporal fossa is so deep that it severely restricts 

 the lumen of the post-temporal fossa. Also seen upon the lateral face of the prootic 

 is a prominent ridge of bone which passes antero-ventrally from the level of the pars 

 jugularis. This ridge, which provided a site of origin for branchial musculature, 

 is present but less pronounced in other species of Osmeroides. 



The trigemino-facialis region is basically similar to that of the type-species, but 

 there are two small differences. Firstly, the profundus ciliaris of 0. latifrons leaves 

 the cranial cavity by a separate foramen, whereas in 0. lewesiensis that nerve ran 

 out from the cranial cavity with the trigeminal nerve. The second difference 

 concerns the path taken by the orbital artery. The condition in 0. lewesiensis 

 has been described (p. 99) and is quite typical of elopiforms. In 0. latifrons (as 

 represented by B.M.N.H. P.11190) an unusual condition existed. The orbital 

 artery pierced the lateral face of the prootic and turned antero-dorsally to pass into 

 the orbit immediately beneath a small bridge of bone, without taking its usual path 

 through the pars jugularis. The path of the orbital artery presumably resulted 

 in the efferent hyoidean branch looping back into the pars jugularis before running 

 out of the prootic with the hyomandibular ramus of the facial. Since only one 



