34 F, L. LANDACRE 
1X0 PISO 
Text figures 1, 2 and 3 are camera tracings through the region of the IX gill 
from a 9.7 mm. embryo of Lepidosteus. 
Fig. 1 passes through the point of contact of the first true gill with the roof of 
the pharynx. 
Fig. 2 passes through the aati gill shelf (ec.) seven sections posterior to 
fig. 1 
Fig. 3 passes through the epibranchial placode of the IX and through the ante- 
rior end of the general visceral IX. The resemblance stucturally between the 
ectodermic gill shelf and the placode is striking. The placode can be recognized 
by its darker color. 
Aud.V., auditory vesicle; Aud., auditory ganglion; B.V. blood vessel; Br.A, 
branchial “artery ; ; E.P.IX, epibranchial placode of IX; Hc., ectoderm of ea shelf; 
G.V.IX, general visceral ganglion of IX; Met., Metencephalon; No., notochord; 
Pr.L.L., primordium of lateral line. 
