570 GILBERT C. BOURNE. 
may be seen in the position of these openings. For the 
reasons already stated I am unable to throw much lght on 
these structures by the study of sections, but, as far as my 
sections show anything, they support the view that they are 
the openings of a pair of glands. If this is the case, there 
is a pair of glands opening in the same position as 
the “green-glands” of the Decapods and some Amphipods ; 
for it must be conceded that, although the second antenne are 
absent in Monstrilla, these openings occupy the place in which 
they would be found were they present. Claus describes a 
pair of “shell-glands ” in the nauplius of Cyclops opening on 
the bases of the second antenne (‘ Freilebenden Copepoden,’ 
p. 60, Taf. i, fig. 8). A reference to Claus’s memoir will show 
the relation of the known antennary glands of Copepoda to 
the openings in Monstrilla, and a short discussion on their 
morphological significance is given in the same place.! 
The mouth opens on a small cone on the ventral surface of 
the head. In Monstrilla viridis and M. helgolandica it 
is situated nearly in the middle of the first body-segment, but 
in other species it is placed more anteriorly, not far behind the 
antenne. It leads into a pharynx with tolerably thick walls, 
which is connected by a string of tissue, thicker in some species 
than in others, with the hypodermis. 
The only other feature in the external anatomy which calls 
for special mention is the appendage of the first abdominal or 
genital segment. 
In the females of the majority of the species of Monstrilla 
this has the form of a pair of stout sete, the bases of which 
enclose the genital aperture. The setz are somewhat swollen 
and flexuous towards their extremities and end in fine points 
1 The “green-glands”’ of the Malacostraca are not the homologues of the 
« shell-glands ” of Phyllopods, which open at the base of the fifth pair of 
appendages (second maxille) ; whereas the sreen-glands belong to the second 
pair of antenne. The glands described by Claus in the nauplius of some 
Copepods are therefore the homologues of the green-glands of the Decapods ; 
and the glands of Monstrilla, if I am right in believing them to be such, 
would have the same homology. Vide Claus, ‘ Untersuchungen des Crus- 
taceen Systems,’ Wien, 1876, p. 28. 
