Macteay MemoriaAL Voueme. 
— 
(oe) 
io 0) 
The main conclusion from the observations recorded in this paper may be 
expressed as follows :— 
The prenasal portion of the axis of the embryonic chondr« cranium — a prolon- 
eation of the intertrabecular cartilage—does not disappear in the course of the 
development of the skull of Platypus, and it not only persists but attains a high 
deeree of structural development fart passu with the great increase of the facial 
skeleton of this animal, and actually assumes considerable functional importance as 
part of the skeleton of the snout or muzzle. 
Finally, we wish to express our thanks to Mr. J. J. Fletcher for his kindness in 
placing several papers at our disposal for consultation ; and to Mr. Robert Grant, 
the able assistant in the Physiological Laboratory, for much practical assistance. 
REFERENCES. 
(1) Huxtey. “Anatomy of Vertebrates,” Edition 1871, p. 322. 
(2) Owzn. “ Comparative Anatomy of Vertebrates,” 1868, III. pp. 383-4. 
) Frower (and Gapow). “ Osteology of the Mammalia,” 3rd Edition, 1885, p. 243. 
(4) Mivarr. “ Lessons in Elementary Anatomy,” 1879, p. 247. 
(5) WarerHousE. “ Natural History of the Mammalia,” 1846, I. p. 29. 
(6) Mecken. “ Ornithorhynchi paradoxi descriptio anatomica,” 1826, Tab. VII. 
(7), Parker, W. K. Mammalian Descent,” p. 45. 
(8) Rupotrui. Quoted by Meckel (Zoc. czt.). 
(9) Mecxet. (Loc. czt. p. 20.) 
(10) Owen. Article “ Monotremata” in Todd’s Eneyclop. Vol. III. 
(11) Owen. “Comp. Anat. of Vertebrates,” Vol. IL. p. 322. 
(12) Firower. “ Osteology of Mammalia,” Edition 1876, p. 219. 
(13) Atsrecur. “Sur la Fente Maxillaire et les 4 os intermaxillaires de P?Ornitho- 
rhynque,” Bruxelles, 1883. 
(14) Turner. “On the dumb-bell-shaped bone in the palate of Ornithorhynchus,” 
Journal of Anatomy and Physiol. Vol. XTX. p. 214-5. 
