Report on the Crustacea Schizopoda of Ireland. 247 
Distribution.—Start Bay, Devon: off Plymouth (E. W. L. H. and W. I. B.). 
Trish Sea (A. O. W.). 
Naples (M.-Edw., G.O.S., Czerniavsky): Algeria(?) (Lucas). 
We found this species extremely abundant in Start Bay in 1898,f while 
later in the same year a single specimen was recorded from the Irish Sea by 
Mr. Walker.{ Our present record deals with material collected nine years ago, 
so that it is improbable that the appearance of the species in British collections 
is due to a recent extension of range. Mr. Walker speaks of the difficulty of 
distinguishing this form from Leptomysis apiops, G. O. Sars, but the latter has a 
smooth skin, while that of D. longicornis is most conspicuously hispid. | 
The synonymy of the species is chiefly the result of the misplaced industry of 
Czerniavsky, who, mistrusting the identity of Sars’ species with the imperfectly 
defined MW. longicornis of Milne-Edwards, changed the specific name of the former 
to A. platydens, while nevertheless including Milne-Edwards’ species in the genus 
of which Sars’ species was made the type. At the same time a new species, 
A. spinosissima, was erected for the reception of specimens, also from the Bay of 
Naples, which do not appear to us to differ from the type in any essential 
feature. Since no note is made of the character of the skin in Czerniavsky’s 
dichotomic table (op. c7t., p. 187), it may be presumed that A. spinoszssima is as 
hispid as D. longicornis. In the same table the dimensions of the two species have 
been transposed, A. spinosissima being in fact founded on specimens considerably 
smaller than those described by Sars. To this difference in size may, perhaps, be 
ascribed such discrepancies (other than those of slight abnormality of the telson, 
cf. Pl. xxxt., fig. 19) as Czerniavsky was able to detect. 
Sub-family.—MysIpDELLINz. 
Genus Mysidella, G. O. Sars. 
Body short and robust. Eyes well developed or rudimentary. Antennal scale 
small, lanceolate, setose on both margins. Peduncle of antennule in male with only 
avery small hirsute lobe. Zabrum obtuse in front, produced behind into two unequal 
lobes. Mandible large, the incisive extremity very much dilate and flattened, in 
the form of a blade without a trace of teeth or spines. rst mawilla, its processes 
strongly incurved; the outer large, compressed, sub-spathulate, with obliquely 
+ Journ. WU. B. A., N.S., v., 1898, p. 344. 
t Ann. Rep. Port Erin Biol. Stat., 1898, p. 15. 
2M 2 
