1912-13.] Pseudo-hermaphrodite Examples of Daphnia pulex. 315 
The parent of the abnormal specimen above described came under 
observation, in one of Dr Agar’s cultures, in May, 1910. It was normal, and 
produced two broods, all the members of which were normal females. The 
third brood consisted of fifteen females, fourteen normal ones and the speci- 
men just described. It is worthy of record that the fifty-seven young 
produced by the fourteen sisters of this aberrant specimen were all normal 
females. Thus, among all the available relatives of the aberrant specimen, 
including its parent, sisters, nieces, children, and grandchildren, altogether 
383 individuals, not one was abnormal. 
Investigation of the abnormal specimen proves it to be a female in 
which only one character — the right antennule — exhibits any departure 
from the normal. This appendage is clearly of the same type as that of a 
Fig. !). — The aberrant right antennule of specimen IV., right aspect, x 300. 
F., flagellum ; O.F . , olfactory filaments ; S., seta. 
male Daphnia pulex, but actually surpasses the latter in the grade of 
development of its parts. All the known relatives (383 were examined) of 
the specimen were found to be entirely normal. 
IV. Dr Agar’s second specimen was found among a large number taken 
near Glasgow on September 12, 1909. All its characters agree with those 
of a female, except the right antennule (fig. 9), which is much larger than 
the normal female antennule present on the left side of the same specimen, 
and bears distally a large flagellum, movable in life, as well as olfactory 
filaments of the usual form and number. The basal part of this appendage 
is considerably shorter than that of a male D. pulex, is of different shape, 
and a seta is not present on its anterior margin. The nearest counterpart 
of this aberrant antennule appears to be the antennule of a female Cerio- 
daphnia reticulata ( Jurine), but the former is considerably larger than the 
latter in all its parts. Dr Agar tells me that the trunk-appendages of both 
sides were those of a female, and that both ovaries were well developed and 
