70 ON THE GENUS LATHAMUS. 



hinder margin of these parts, as seen from above, is not very far from 

 being on a level with the cranio-rostral suture, and so causes the orbits 

 to take up a larger part of the surface of the skull (in a view from 

 above) than in the other group. The same is the case in Lathamus * 

 (PL I. fig. 10). 



The retention of the furcula is no doubt associated with the rapidity 

 of flight of this bird, whilst in the more slowly moving Platycerd it has 

 disappeared almost entirely. As we already know from M. Blanchard's 

 researches (Ann. Sci. Nat. Zool. xi. pp. 84-85, 1859), but little assistance 

 as regards classification can be gained in this group from a study of the 

 sternum. 



The pelvis, however, has been of more use to me. 



In the Lories this is always elongated and narrow in proportion, the 



preacetabular part being particularly elongated, and the iliac fossae on 



each side for the attachment of the gluteal muscles being deeper and 



P. Z. S. 1879, more extensive. In the Platycerd and Lathamus the pelvis is wider, the 



p. 174. preacetabular part much shorter, and the iliac fossae shallower and 



smaller. These differences will be visible from the figures which I 



exhibit (PI. I. figs. 11, 12), in which are shown respectively the pelvis 



of Lathamus and of Lorius tricolor. 



As regards internal anatomy, little can be said of any important 

 characters, except the difference in the disposition of the carotid arteries 

 in the two groups, first pointed out by Prof. Garrod, and already men- 

 tioned above. The nature of the tongue in Lathamus requires reexami- 

 nation, as also does the coloration of the eyes, this presenting very 

 marked characteristics in all those Trichoglossinse I have been able to 

 examine alive (of the genera Lorius, Eos, Chalcopsitta, and Trichoglossus), 

 and being quite unlike that prevalent in the Platycerd and most other 

 Parrots. 



In coloration Lathamus is no doubt aberrant, but is no more clearly 

 related, as far as I can see, to one group rather than the other. The 

 external rectrices being blue is perhaps a hint of its Platycercine 

 relations. 



To conclude, the more important characters of Lathamus, i. e. pterylosis 

 and superficial left carotid, beaks, nostrils, cere, feet, skull, and pelvis, all 

 point to a near relationship to Psephotus, Platycercus, and allied genera. 



* Bonaparte (Compt. Rend. xliv. p. 536, 1857), following Owen (Cat. Osteol. Series 

 E. C. S. 1853, p. 279, no. 1451), says that in Lathamus the orbit is completed below by 

 the junction of the lacrymal with the " mastoid." This is certainly not the case in a 

 skull lent to me by Professor Garrod, and, if true, would be an anomaly for any 

 member of either of the above-mentioned groups. In the specimen referred to in the 

 Museum of the College of Surgeons (no. 1451) it appeared to me on examination that 

 there was in reality no bony union between the two bones, which were connected 

 simply by ligament. 



