124 PEOFESSOE OWEN ON THE GENUS DINOENIS. 



On a first view of the pelvic viscera, as exposed by removal of the intestines, the kidneys 

 appear to be chiefly developed anteriorly, the broad lobes there extending beyond the 

 ilia with a convex border covering, or lying in contact with, part of the iliac origins of 

 the abdominal muscles. The length of these anterior renal lobes equals that of the 

 antacetabular part of the pelvis in Aptornis defossor ; the second lobes, commencing 

 mesiad of the anterior ones, acquire their greatest breadth where those terminate, but 

 are here much narrower than the anterior lobes. Thence the middle lobes contract 

 transversely to a point, underlapping the narrow posterior lobes, which seem to end 

 where the ischia join the sacrum, and to blend with each other ; but it is merely 

 close contact, they are distinct ^ 



On each side of the hind part of the kidney is the beUy of the " obturator internus " or 

 postrenal muscle, which underUes the inferior opening of the ilio-ischial excavation. 



This muscle being removed, the renal substance is found to pass " neurad," expanding 

 to a breadth equal or superior to that of the anterior lobes, with much greater depth 

 or thickness in the neuro-haemal or dorso-ventral direction ; and this the true posterior 

 renal lobe is shown, by a vertical longitudinal section of the side of the pelvis, to fill the 

 whole of the great posterior ilio-ischial cavity, extending from the partition bounding 

 posteriorly the interacetabular cavity backward to above and beyond the ischio-iliac 

 deck-like plates (PI. XV. fig. 2, v'). 



The vertebrae numbered 19, 20 in PI. XV. fig. 2 are homologous with the first two free 

 caudals in Eallus aquaticus and Ocydromus australis. The parapophyses of the seven- 

 teenth and eighteenth sacrals expand, coalesce (a small foramen intervening), and unite 

 with the " deck " («'), of which they form the inner beginning. The parapophyses of 

 the first caudal in Eallus abut against the ilia, leaving a small intervening foramen 

 between them and the antecedent parapophyses. The homologous foramina are seen 

 on each side of the vertebra 19 in fig. 2. PI. XV. 



From these foramina each ilium extends backward 2 inches. The free terminal ends 

 bend slightly toward each other, leaving an interval of 9 lines; they are obtusely 

 rounded. Externally each is strengthened by a vertical ridge (PL XIV. fig. 1, 1). 



The entire length of the ilium, following the upper curve, of Aptornis defossor is 

 12i inches, equalling that of the same part of the pelvis in Casuarius hennettii. This 

 length is pretty equally divided by the mesial beginnings of the "gluteal ridges" 

 (PI. XV. fig. 1,^). 



The fore half of the ilium repeats very closely the characters of that part in Aptornis 

 otidiformis^. The upper curve is greater in Aptornis defossor; the gluteal ridge is 

 stronger, runs more outward, and ends by an obtuse process (PI. XPV. fig. 1, A). The 



1 In my 'Anatomy of Vertebrates,' the statement (vol. ii. p. 227) that "the kidneys are more or less 

 blended together at their lower extremities in the Coots (FuUca) " will probably bear the above explanation. 

 I am indebted to our excellent Secretary, Mr. Solater, for the subject of the above dissection. 



• Trans. Zool. Soc. vol. vii. p. 366, pi. 42. fig. 1, pi. 43. flg. 1. 



