GREGORY: FISH SKULLS 



243 



cipital region pass above the dermal skull roof, between the long and well-braced ridges shown 

 in Figure 117, while in the tarpon (Fig. 32) these muscles pass beneath the dermal skull roof, 

 entering through the large posttemporal fenestrae and running immediately above the endo- 

 cranium itself. In both cases the otic region has to receive the downward and backward 



de/h 



sphot 



Luc/o/afes 



pa pto 



Fig. 117. Luciolatfj sp. Neurocranium, showing strengthening crests and ridges. 



thrusts resulting from forward locomotion, etc., but in the tarpon the thin supraoccipltal 

 is widely separated from the frontals, while in Luciolates the supraoccipital is suturally 

 wedged in between the dominant frontals and braced laterally by stiff ridges on the frontals 

 and pterotics. In fact, the supraoccipital is the keystone of the occipital arch even to a 

 greater extent than in the tarpon. Hardly less important are the backwardly-projecting 

 epiotics, to which are attached one of the horns of the supratemporal, conveying wrenching 

 and pulling forces from the shoulder-girdle. The epiotic is well braced by the parietals, 

 exoccipitals, etc., to meet these demands. 



The otic region itself is highly adapted to receive thrusts coming from various direc- 

 tions. The supraorbital frontal roof is beautifully braced by an obliquely-placed buttress 

 on the sphenotic, which when held up to a strong light, in the side view may be seen, as it 

 were, to gather together its trabeculse and direct them downward and backward across the 

 prootic to the stout basioccipital. Lesser bundles and strands of trabeculae may be traced 

 in various directions through the occipital region. For instance, in the top view, especially 

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