182 



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. Id, which was attached to one of the plates by a dorsal thread. 



And lastly, in the marsupium of an Er. 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 XII, fig. 2 a— 2 i). 



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 pi. XI, 

 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. Antennulae (a) rather short, 2-jointed, basal joint thick, second 

 joint short, terminating in some short setae 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 turned 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. 2 b), with a hole (h) at its anterior end. (This hole, no doubt, is the 

 orifice of a gland, and — strangely enough — T have not been able to find it in the pre- 

 ceding species, but I have found it in Aspidoecia and in Spliceronella Munnopsidis ; however, 

 I 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 



