BY R. BROOM. 213 



REFERENCES TO PLATES X.-XVII. 



al.n., alinasal — a.n.^ anterior nares — a.Pmx., trace of the premaxillary 

 extending round the front of the nasal capsule — a.s , alisphenoid — and. 

 auditory capsule — b.hy., basihyal — car., carotid artery — c.f., carotid fora 

 men — coch., cochlea — covj., conjunctiva — D., dentary — d.e.L, ductus endo 

 lymphaticus— d.^., dental lamina — e.a.c, external auditory canal — e o. 

 exoccipital— /.e., foramen epiphaniale — G.g., Gasserian ganglion — hy. 

 hyoid — in., incus— J. o., Jacobson's organ — Ju., jugal — lab., labyrinth — 

 ma., malleus — ML, Meckel's cartilage— if a;., maxilla — n.s., nasal septum— 

 O.S., orbitosphenoid — Pa., palatine — pit., pituitary — Pmx., premaxilla — 

 p.s.f paraseptal cartilage —P^.. pterygoid — s.e.L, saccus endolymphaticus — 

 S.O., supraoccipital — s.p., secondary palate— <Ay., thyro-hyal — tr., trabecula 

 — t.L, tegmen tympani — tymp., tympanic cavity — ut., utricle; v., vii., viii., 

 ix., X., xi., xii., cranial nerves — viLg^, ganglion of nerve vii. — viii.c, cochlear 



ganglion of nerve viii. 



Plate x. 



Fig.l. — Underview of reconstruction of the skull of a 10 mm. intrauterine 

 foetus of Trichosurus vulpecula{ x 22). The parts outlined are dis- 

 tinctly chondrified; in those parts which are coloured, but with 

 dotted outlines, chondrification is imperfect; the parts shaded but 

 not coloured are not chondrified. 



3Figs.2-5.— Sections through the snout of 10 mm. Trichosurus embryo( x30). 



Plate xi. 

 Figs.6-7.— Sections through the alisphenoid region of the head of 10 mm. 



Trichosurus embryo( x 30). 

 JFigs.8-9. — Sections through the ear-region of head of a different specimen 



of 10 mm. Trichosurus embryo. Cut in different direction( x ). 



Plate xii. 



Fig_10. — Under view of reconstruction of skull of 14 mm. mammary foetus 

 of Trichosurus vulpecula{x^O). The membrane bones are removed 

 from the right side; and Meckel's cartilage, the malleus, incus, 

 stapes and hyoid from both sides. 



Fig. 11. — Side view of same( x 30). 



Fig. 11a. — Malleus, incus, and stapes of ditto. 



Plate xiii. 

 Figs. 13-16.— Sections through the anterior part of the head of 14 mm. 

 mammary fcetus of Trichosurus vidpecula{ x 45). 



Plate xiv. 

 Figs. 17-20. —Sections through the middle region of the head of 14 mm. 

 mammary foetus of Trichosurus vidpecula{x^O). 



