by Frank E. Beddard. 147 
ments given by that authority an asymmetry between the lengths of 
the fins of each side. I could detect no marked difference in form 
between the two fins of the younger of the two embryos studied by 
myself; but I find (see text-fig. 13) that the left fin of the larger feetus 
has a straighter lower border than the right fin. I also agree with 
Hentschel in finding some difference in size. As the matter depends 
upon very minute differences I obtained through the kindness of Miss 
TExtT-FIG. 13. 
1S. 
OLDER Fartus. 
Right (B) and left (A) pectoral fins. This shows the slight asymmetry of the 
two. The outline of the digits, with the exception of the small pollex, are 
seen. The fifth longitudinal fold near the edge 6 does not represent a digit. 
Kathleen Lander, M.Se., Lond,. Acting Prosector of the Zoological 
Society, additional measurements to check those made by myself. In 
the youngest fetus I found the greatest length of the free region of 
the fore limb to be 12 mm. in the case of the right limb and 11 in the 
