920 THE AMERICAN NATURALIST. [Vor. XXXIV. 
far as the upper part of the abdomen. The organs of the 
pelvic end of the abdomen and the character of the muscles 
can be more advantageously studied in other series and stages. 
I2 
is Ven. 
Of, 
DE: New. 
7.6 
5 
Fib: 
D.E., ductus 
s. Transverse section 185. ; 
; Ven., hind-brain 
Fic. 2.— Pig embryo of 12.0 mm. Series No. 
endolymphaticus; 7.5., fore-brain; Neu., neuromere; Of., 0 ; al 
(fourth ventricle); 5, trigeminal nerve; 7.8, acustico-facial nerve; 9, glossopharynge 
nerve; 70, vagus nerve; 72, hypoglossal nerve. x 22 diams. 
Fig. 2 is at a level about halfway between the eye and the 
highest point in Fig. 1; it passes, therefore, through the fore- 
brain (F...) and the fourth ventricle ( Ven.) or cavity of the 
