ANATOMY OF THE MELANONIDAE 



17 



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esc 



exo 



pro f/X bo v1 



Fig. 5. Neurocranium of M. zugmayeri in A, posterior and B, lateral views. In B, the intercalar is unshaded, the margins of the bones 

 underlying it indicated by dashed lines. C, parasphenoid of 66mm SL specimen in dorsal view. 



frontal, parietal and pterotic. The underside of the bone 

 bears a deep, almost transverse fossa into which articulates 

 the hyomandibular. The pterotic (Figs 4A,B, 5A,B) accom- 

 modates the posterior portion of the hyomandibular fossa 

 along a third of its lateral border. The wall of the pterotic is 

 somewhat bullate and its cranial surface forms a prominent 

 lateral shelf. 



The pterosphenoid (Figs 4B, 5B) is long and deep forming 

 most of the dorsomedial wall of the orbit, anteriorly it 

 contacts the frontal and posteriorly the autosphenotic and 

 prootic. The parasphenoid (Figs 4B, 5B,C) has a broad keel 

 with, extending from its centre, a long, low ascending process 

 which extends laterally at a low angle to the horizontal plane 

 to meet the prootic; paired, parallel laminae rise from the 

 central region of the keel to meet the bases of the lateral 

 ethmoid wing (Fig. 6). 



The prootics (Figs 4B, 5B) are large with a deep trigeminal 

 notch. The posterior border of the bone is rounded and 

 partially overlapped by a relatively small, ovoid intercalar to 

 which is attached the inferior limb of the 

 posttemporal(Figs 4B, 5A,B, 6D). The small, pinnacle-like 

 epioccipitals contact the posterolateral margins of the 

 supraoccipital and posteriorly the dorsal borders of their 

 respective exoccipitals; laterally each epioccipital is overlain 

 by the second extrascapular (Fig. 4A). 



The exoccipitals are deeply depressed posteriorly and con- 

 tain a large, backwardly facing vagus foramen (Figs 5A,B, 7). 

 Medially, the bones meet across the midline by flange-like 

 projections. Posteriorly there is an ovate, cartilage-filled 

 process the base of which meets its antimere in the midline. 

 Inside each exoccipital a long, ventrally directed process 

 extends from the medial surface to contact a shallow dorsal 



