ete © ee iestes 
Soe eee ee ee Sr 
ST) Oe ele ee ee eee . 
~~ the Mouth in Sucking Crustacea, 21 
part some few hooks—the middle one three, the innermost 
only one. . 
n the male Cymothoa the sides of the mouth-tube are, as 
we have stated, supplied by the _maxilliped-palps, which 
reach as far as the labrum; and the maxillary lobes of the 
second pair have therefore here, as in 4ga, no other duty 
than to fill up the slit between the maxilliped-palps, though 
certainly this opening is proportionally larger in Cymothoa, 
the palpi in question being smaller and the lobes of the maxil- 
bods wanting. But in the female Cymothoa, where the 
maxillipeds do not enter into the construction of the mouth- 
tube, this devolves entirely on the second pair of maxille 
(x*, fig.6a; the maxillipeds are removed). ‘These are there- 
fore much broader than in the male; their stems meet in much 
greater extent, namely with the whole of their front halves, 
and the lobes form together a large curved lip, which, on the 
sides, joins the labrum. 
_ Although this conversion of the maxillary lobes of the 
second pair into a kind of lip in all essential points makes up 
for the non-participation of the maxillipeds in the construc- 
tion of the mouth-tube in the female, and their limited parti- 
cipation in the male, this expedient would, nevertheless, not 
be sufficient if the labrum in Cymothoa were not larger than 
in 4¢ga. But whilst in this latter genus the labrum occupies 
only one-third of the circumference of the mouth-tube, it sup- 
in Cymothoa quite one-half. It is consequently much 
roader, much more considerably arched from the top down- 
wards, so that it becomes like an inverted cup when the mouth- 
tube is contracted; a small undulation is then also observed 
in the middle of the margin, which latter is furnished with 
numerous minute warts. But when the mouth-tube is dis- 
tended and examined from beneath, the margin appears undu- 
lated or crenate. 
- From all this it appears that the mouth-tube is, upon the 
whole, softer and less powerfully armed in Cymothoa than in 
Aiga: instead of the alae fringe-like covering of warts on 
the labrum, the considerable bundle of hooked spines on the 
palpi of the maxillipeds, and the row of spines on the turned- 
over margin of the maxillary lobe of the second pair in Aga, 
we find in Cymothoa merely the very minute warts ‘on the very 
edge of the labrum and on the cushion-like lobes of the second 
pair of maxille, and the very short row of hooked spines on the 
two innermost cushions of these lobes and on the margin of 
the terminal joint of the maxilliped-palpi in the male. But 
this weaker armature of the mouth in Pedishor of course cor~ 
