URINARY ORGANS OP THE AMPHIPODA. 
187 
Mayer 1 has also described them in the Caprellidae, where he 
states that they are well developed in Caprella, and absent, or 
only very feebly developed, in Protella, Proto, and Podalirius, 
but when present he has never found in them characteristic 
concretions, and is very decided in asserting that throughout 
the Amphipoda these diverticula, whatever may be their func- 
tion and whether they contain excretionary products or not, 
belong morphologically to the mid and not to the hind gut, and 
that hence they cannot be considered as analogous to the 
Malpighian tubes of insecta. He states that there is always 
present a sharp break in the epithelium where the mid and 
hind gut meet, and that the chitin lining of the latter is not 
continued into the tubes whose epithelium resembles that of 
the mid, and not that of the hind gut. 
I have lately carefully investigated the nature of these tubes 
in numerous specimens of Talitrus locusta, where they may 
without any difficulty be discerned by carefully removing from 
the animal the whole of the alimentary canal, and after laying 
this out upon a slide gently separating the two tubes from the 
side of the hind gut close to which they lie though clearly dis- 
tinguishable by their whitish colour. 
Fig. 1 represents part of the alimentary canal of Talitrus 
which has been removed from the body with the tail segment 
still attached, though the liver tubes when in the body would 
lie in the contrary direction. The figure is drawn to scale, 
and shows the relative length of the parts. 
When compared with fig. 5 of Gammarus a point of con- 
siderable difference between the two is seen at once, the tubes 
in Talitrus opening at a considerable distance from the anus 
and running backwards instead of forwards, as in the former, 
to end blindly in the last segment. They are, indeed, very 
similar to the Malpighian tubes of insects, more especially 
resembling those of such a form as Julus, where only one pair 
is present. 
Fig. 2 represents a transverse section through the hind gut 
of Talitrus in which the two tubes are seen lying some distance 
1 ‘ Die Caprelliden des Golfes von Neapel,’ p. 147- 
