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Between the marsupial plates of the host were further found: three males, two of them 
attached by frontal threads to a marsupial plate, on its edge and a little inside it on the 
surface; and finally: the minute pupa drawn in fig. 3i, and the very young female represented 
in fig. 1d, which was attached to one of the plates by a dorsal thread. 
And lastly, in the marsupium of an Lr. abyssorum, infested with the following 
species (to which we refer), occurred a very young female which adhered to the female of 
the other species. 
2. Mysidion abyssorum n. sp. 
(PL. XI, fig. 2a—2). 
FEMALE. A specimen containing fourteen ovisacs was 1°39 mm. long and ‘965 mm. 
broad; its shape much like that of the specimen of Mys. commune represented on pl. XJ, 
fig 3b, but its head was not turned upward on the dorsal side, it was placed as usual 
anteriorly and, if anything, on the ventral side. The general outline of the head as 
in the preceding species. Antennule (a) rather short, 2-jointed, basal joint thick, second 
joint short, terminating in some short sete and a much longer olfactory seta. No taps 
on the anterior side of the head. The basal joint of the maxilla has on its terminal 
margin two good-sized processes, one of them near the centre, the other at its posterior 
end. The maxillipeds are armed with a conspicuous spine at the distal inner angle of 
the penultimate joint. The part of the head which corresponds to the lateral border is 
furnished in its whole length with a fairly broad belt of rather short hairs, and some- 
what behind the base of the maxillipeds we see a very good-sized, odd, triangular area, 
covered with moderately short hairs; the longest line of this triangle is tured towards the 
front, the opposite hindmost angle is on the median line; and finally, on each side, between 
the maxilla and the maxilliped, is a rather small, transverse, hair-covered area. On the 
trunk behind the head we see some scattered hairs. The list of the genital apertures is 
almost semicircular (fig. 2b), with a hole (h) at its anterior end. (This hole, no doubt, is the 
orifice of a gland, and — strangely enough — I have not been able to find it in the pre- 
ceding species, but I have found it in Aspidoecia and in Spheronella Munnopsidis; however, 
IT cannot make out with certainty whether it is one tolerably large hole, or perhaps rather 
a small area with a very thin membrane pierced with a number of small holes). 
MALE. A specimen of normal size is ‘164 mm. long, nearly of the same breadth 
and somewhat flattened (fig. 2e and fig. 2f), thus of small size compared with the female. 
A couple of specimens were abnormally small, one of them only 099 mm. in length (their 
size in proportion to the normal male is shown by comparing fig. 2d and fig. 2c), similar in 
shape to the larger specimens, so these males are considerably smaller than any other male 
of this family, but it remains an open question, whether they are adults, or — perhaps more 
