1908-9.] Development of Auditory Ossicles in the Horse. 601 
Fig. 5. Auditory ossicles of a horse at term (the hones are here fully ossified), 
magnified three diameters. 
Fig. 6. Section through the first and second pharyngeal pouches and the first 
gill furrow of an embryo aged five weeks (length 12 mm.). x 32 diam. 
Fig. 7. Section through the auditory sac of the same embryo. x 54 diam. 
Fig. 8. Section through the proximal end of Meckel’s cartilage and the 
anlage of the malleus of a horse embryo aged five weeks. Blue represents pro- 
cartilage. x 66 diam. 
Fig. 9. Section through the maleo-incus articulation of the same embryo, 
x 208 diam. 
Fig. 10. Section through the stapes and incus anlagen of the same embryo, 
x 42 diam. 
Fig. 11. Section dorsal to fig. 10 through the stapes anlage of the same embryo, 
showing the arteria stapedialis. x 36 diam. 
Fig. 12. Section through the stapes and incus (crus longum) of an embryo aged 
about three months. The cartilage is shown blue. The stapes, incus, and vestibular 
portion of the auditory capsule show the beginnings of ossification. x 42 diam. 
(Issued separately September 9 , 1909 .) 
