Rey. T. R. R. Stebbing on the Genus Bathyporeia. 75 
in the figure of B. pilosa, very long in that of B. pelagica, 
and of intermediate size in that of 5. Robertsont. But in the 
order Amphipoda, as with the facets of the eyes, so with the 
articuli of the lash of the antenne, an increase takes place 
with advancing age. ‘This part of the animal will not, there- 
fore, of itself suffice for the establishment of a specific distine- 
tion. Still the figure with the lash of intermediate size has a 
character not attributed to either of the other forms. The 
distal end of each articulus of the flagellum is surmounted by 
an ornament in the shape of an elongated horse-shoe, to which 
Mr. Stimpson has given the name “‘calceola,” informing Messrs. 
Bate and Westwood that it is a character of the male sex. 
In their description of Lystanassa longicornis these authors 
express the opinion that the “ calceole’’ have the power of in- 
creasing the sense of smell to a more acute degree. In de- 
scribing Bathyporeia Robertsont they mention the additional 
circumstance that in the upper antenne each articulus bears 
“a short auditory cilium of an oval form.” Fritz Miller 
mentions, in his ‘ Facts for Darwin’ (‘Translation by Dallas, 
p- 20), that he considers these “ auditory cilia” of the upper 
antenne to be olfactory organs, fortitying his opinion by the 
fact of their stronger development in the males than in the 
females of certain species, as in other cases male animals are 
not unfrequently guided by the scent in pursuit of the females. 
Whether Bathyporeia appreciates scent and sound by the 
lower and upper pairs of antenne respectively or vice versa, 
or whether to each or either of these purposes it applies both 
of them or neither, is a question for nice and careful experi- 
ment. This much, however, is certain, that the “ calceole,” 
whatever their use may be, were present in those specimens 
which had the antenne about as long as the animal itself, 
thus bringing B. pelagica one step nearer to b. Robertsont. 
Between the short flagellum and the long one the difference is 
considerable, the former having only some seven or eight articu- 
lations, while in the latter I counted thirty-two. It should also 
be stated that on none of the short flagella did I observe the 
slipper-shaped appendages, although the specimens of this form 
were considerably more numerous than those of the other two. 
On the other hand, I took the form that has short antenne 
with the young upon it, establishing the point that this is a 
female form, though leaving it an open question whether its 
mate in all respects resembles it. The young just born had 
a strong family likeness to their mother. There did not seem 
to be any long antennae among them; nor were they to be 
expected. 
Of the other parts of the animal one description will equally 
