146 Anatomy of Sperm Whale Fetus 
length is one-third of the cloacal groove. Here, too, the mammary 
grooves are parallel with the cloacal groove. I lay stress upon this 
position since Kiikenthal represents the mammary grooves in his female 
foetus as lying at an oblique angle with the median genital groove. As, 
however, the adjacent areas are rather contorted in appearance in his 
figure, it is possible that this contortion—the result perhaps of 
contraction during preservation——has affected the mammary grooves. 
They are only 4 mm. long in this fetus and have thus a different 
proportion to those seen by myself. 
Text-Fig. 12. 
M.G, 
ee 
OLDER Farus. 
Ventral surface of cloacal region. M.G. = mammary groove of one side. 
2 = pans, 25 = as, 
PECTORAL FINS. 
The position and general shape of the fore limbs can be understood 
from an inspection of Plate XXIII. The lower anterior border 
of the limb is longer than the upper ; it is also straighter—the upper 
border is a curve of nearly one-quarter of a circle. The two fins of the 
adult whale are stated by Hentschel to be strongly asymmetrical in 
shape and both are incidentally figured by him in illustration of this 
difference.* Furthermore, there is ascertainable from the measure- 
* loc. cit., figs. 1 and 8. 
