32 PROF. d'aECY W. THOMPSON ON THE [Jail. 17, 



plete, and in all these the postfrontal process is extremely reduced, 

 forming only a short protuberant edge as in Eclectus. In all the 

 squamosal process is well developed : it is especially long and 

 straight in Pachi/nus, in which it nearly meets the prefrontal ; the 

 latter process is much shorter in Pixoceplmlus than in the other 

 two. In Pachyims the basiteniporal ridges are faint, and the 

 surfaces external to them and extending back to the paroccipifals 

 are much flattened, the paroccipitals being directed backwards ; 

 thei-e is no trace of descending maxillary processes. In Caica the 

 basiteniporal ridges are much stronger ; in all the basiteniporal 

 plate is nearly on a level with the occipit;il condyle. The auditory 

 meatus is somewhat narrower and more notched above and below 

 than in Clirysotis, and the interspace between it and the occipital 

 ridge is somewhat greater. The quadrate in Caica and Puchynus 

 has a high posterior prominence above and behind the socket for 

 the jugal, as in Conurus. The mandibular fenestra is large in 

 Caica, small or obsolete in the other two. 



Family Psittacin^. 



The skull of Ps. eriiJiacus has been considered already. I have 

 also studied the skulls of Coracopsis vasa (fig. 27) and C. niyra, 

 and an imperfect specimen of Dasyptilus pecq^ueti (fig. 28). 



Fig. 27. 



Coracopsis vasa. 



The skulls of these Parrots bring us face to face with the 

 problem of whether Coraco'psis and Dasyptilus are I'ightly placed 

 in so close a relation to Psiltacus ; in other words, with one of the 

 dubious and crucial questions that osteology might suffice to solve. 

 1 cannot boast of being able to give a very clear answer to the 

 question, but it seems to me that the skull of Dasyptilus, and in 

 a minor degree that also of Coracopsis, differs in so many points 

 from that of Psiitacus, that they go far to show that the little group 

 of Psittadnce is very dubiously or improperly defined. 



In Coracopsis vasa the postfrontal process is almost obsolete, 

 forming a slight vertical ridge behind which rises the impression of 



