88 
JANE I. KOBERTSON. 
in length, and this, combined with the localised expansion 
of its middle part round the comparatively unyielding right 
Text-fig. 12. 
A. Section throngli the hiilbus cordis at Stage 32, showing* 
continnity of bnlhns ridges 1 and A. b. Section throngli 
the bnlbns at Stage 32, showing continuity of bnlbus ridges 
1 and A. along the transverse jiart of the bnlbns, c. Section 
thi-ongh the ventricle and the proximal end of the bnlbns at 
Stage 31, showing continnity of bnlbns ridge 1 and A. along 
the posterior (dorsal) w^all of the transverse part of the bnlbns. 
B. C.d. Distal segment of bnlbns. B.C.jp. Proximal segment 
of the bnlbns. B. C. t. Transverse segment of bnlbns. 
B. R. 1. Right bnlbns ridge. B. R. 3. Left bnlbns ridge. 
B. R. A. Ridge on anterior (ventral) wall of proximal segment 
of the bnlbns. R. A. Right auricle. V, Ventricle, 
wall, causes it to kink abruptly on itself in this middle 
region, and gives the expanding part the appearance of being* 
