1890.] THE STRUCTURE OF PSOPHIA. 333 



Psophia shows the following points of difference from Grim : — 



(1) The inner margin of the palatines is not greatly bent down- 

 wards to form the inner lamina. 



(2) The vomer ends on a level with the anterior margin of the 

 maxillo-palatineSj it is anteriorly thin and compressed. 



(3) There is no conspicuous .foramen formed at the junction of the 

 quadrato-jugal with the maxilla. 



(4) There are no occipital foramina above the foramen magnum. 

 (.5) The supraorbital margin is produced into a thin, strong, 



sharp-edged area. 

 ((I) It is holorhinal. 



(7) The interorbital plate is much less vacuolate. 



(8) The palatines are wider behind than in front. 

 (D) The temporal fossae are not so extensiAe. 



(10) The surface of the maxillary process of the nasal bone is 

 directed outwards. 



Psophia shows the following points of difference from Ocjdro- 

 mus : — 



(1) The inner margin of the palatines is not greatly bent down- 

 wards. 



(;"») The supraorbital margin is produced into a sharp edge. 



(7) The interorbital plate is not largely vacuolate. 



(8) The contrast between the wider posterior and narrower anterior 

 part of the palatines is not so marked. 



(9) The temporal fossae are not nearly so well marked. 



(11) The lateral ethmoid processes come more nearly into contact 

 witii the descending process of the lachrymal, which very nearly 

 reaches the jugal. 



(12) The skull is relatively broad in the interorbital region. 



(13) The articulation of the quadrate is not hidden by a down- 

 ward growth of the scjiiamosal. 



In ail these points Psophia also differs from Fulicu and Arumides, 

 Crex and Porphyria ; but, in the latter, characters Nos. 9 and 13 offer 

 less-marked differences. The vomer in Crex and Porphyria is a 

 much broader bone, though ending in a point. 



Psophia shows the following differences from O^dicnemus ' : — 



(2) The vomer does not extend beyond the anterior end of 

 maxillo-palatines. 



(3) There is no conspicuous foramen at the junction of the jugal 

 with the maxilla. 



(7) The interorbital plate is not so vacuolate, though the vacuo- 

 lation is slight in (Edicnemus, 



(9) The temporal fossae are uot so well marked. 



' Tlie sharp edge of the su]3raorbilal region is largely due in I'-svphia to a 

 ehain of siqjraorbital bones, which were first made laiown by Parker (■' On the 

 Osteology of the Kagii," loc. vit. p. 503). It is possible that Qidirnciuts aud 

 Rhinochdus, which agree in this pariicular with Pnophia, will be found to have 

 a similar series of ossicles which in the adult become completely fused with the 

 frontals and parietals. 



Proc. Zool. Soc— 1890, No. XXIII. 23 



