FY Dll. R. W. SHUFELDT, C.M.Z.S. 109 



"tubercle is greatly developed. There are large 'marsupial' 

 "bones in both genera." These in Echidna are longer, nar- 

 rower, and more divergent than they are in the Duckbill, 

 where they are triangular and broad at their bases. The 

 sacral vertebra fuse with the pelvic bones in these mono- 

 tremes, and the suture cf the pubic symphysis is almost 

 obliterated. 



The Bones of the Limbs in the Ornithorhynchns and the 

 Echidna are very fully and quite accurately described by 

 Owen (pp. 323-328), while Flower gives us scarcely any- 

 thing on the long bones of the pectoral and pelvic limbs, 

 having devoted the most of his space and descriptive matter 

 to manus and pes, the bones of which are touched upon more 

 or less fully. 



In another connection later on it is my intention to take 

 up more in detail some of the special skeletal characters, as 

 exemplified in the Monotremata — that is, those that do not 

 fall especially within the scope of the present contribution. 



LEGENDS FOR THE FIGURES. 



Plate XVIII. 

 Fig. 1. Left lateral view of the skeleton of an adult 

 Ornithorhynchus anatiiius, No. 2639, Army 

 Medical Museum Collection; male; reduced. 



Fig. 2. The same skeleton as shown in Fig. 1, seen directly 

 from above, 



Plate XIX. 

 Fig. 3. Superior view of the skull of the specimen of the 

 Ornithorhynchus shown in Figure 1 of Plate 

 XVIII. (No. 2639, Army Medical Museum 

 Collection.) Lower mandible removed. Zygoma 

 of right side missing. Reduced. 



Fig. 4. Mandible of the adult Ornithorhynchus viewed 

 directly from above; reduced; male. Specimen 

 No. 1304, Army Medical Museum Collection. 



Fig. 5. Superior view of the skull of an adult male 

 Ornithorhynchus anatinus; reduced. Speci- 

 men No. 1304, Coll. Army Medical Museum. 

 This is the skull to which the mandible here 

 shown in Figure 4 belongs. The "dumb-bell- 

 "shaped" bone is plainly shown at d, between 

 the premaxillary bones, which latter are nearly 

 out of sight below the nasals. 



