728 DEVELOPMENT OF THE COMMON PHALANGER, 



laroe and external. Though hair is found on all the parts where 

 hair is found in the adult, the hairs are so small that the embryo 

 still looks quite naked. With the exception of the vibrissse, the 

 few large specialised hairs in other parts, and some longer hairs 

 round the lips, none of the body hairs is longer than half a milli- 

 metre, and almost all the hairs are situated at least half a milli- 

 metre apart. The vibrissie are well developed, and large 

 specialised hairs are also found in the following situations: — Two 

 large hairs above each eye, a row of five large hairs on the cheek 

 under and a little behind each eye, a couple from a median papilla 

 on the posterior part of the smphysis of the lower jaw, a couple 

 from a papilla on the extensor surface of the forearm near its 

 middle, a bunch of 8 or 9 from a large papilla near the union of 

 the middle with the lower third of the flexor surface of the fore- 

 arm, and a couple of large hairs which spring from the inner 

 side of each heel. All these enlarged hairs are at least 6 mm. 

 in length, and the vibrissee are mostly a trifle over 10 mm. 

 in length. The claws of the syndactylous toes are not yet 

 specialised, though large and well formed. The following are the 

 pi-incipal measurements at this stage: — Head, 34 mm.; snout to 

 tail, 127 mm.; tail, 57 mm.; arm, 36 mm.; leg, 34 mm.; foot, 

 17 mm. 



REFERENCES TO FIGURES. 

 Plate XXII. 

 Trichosurus vu/2Jecula. 

 j'ig, l.— Intra-uterine foetus, 8-5 mm., g.l. (damaged). Embryo A. 



r,g. 2. 



Fig. 3. 

 Fig. 4. 



Fig. 5. — Intra-uterine feetus. 14 mm., g.l. Embryo F. 



Fig. 6. ,, ,, 14 ,, ,, ,, G, 



Fig. 7. — Newly bora mammary fcetus, 14-S mm., g.l. Embryo H. 



Fig. 8 — Mammary fcetus, 16 mm., g.l. 



