Report on the Crustacea Schizopoda of Ireland. 247 



Distribution.— ^t^rt Bay, Devon : off Plymouth (E. W. L. H. and W. I. B.). 

 Irish Soa (A. 0. W.). 



Naples (M.-Edvv., G.O.S., Czerniavsky): Alg-eria(?) (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.J 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 Leptomijds 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 M. longicornis of Milne-Edwards, changed the specific name of the former 

 to A. plat)jdens^ while nevertheless including Milne-Edwards' species in the genus 

 of which Sars' species was made the ty])e. At the same time a new species, 

 A. spinosissima, was erected for the recej)tion 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. cit., p. 137), it may be presumed that A. spinosissima 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. PI. XXXI., fig. 19) as Czerniavsky was able to detect. 



Sub-family. — Mysidellin^. 



Genus Mysidella, G. 0. Sars. 



Body short and robust. Eges well developed or rudimentary. Antennal scale 

 small, lanceolate, setose on both margins. Peduncle of antennule in male with only 

 a very small hirsute lobe. Lahriim obtuse in front, produced behind into two unequal 

 lobes, 3Iandihle large, the incisive extremity very much dilate and flattened, in 

 the form of a blade without a trace of teeth or spines. First maxilla, its processes 

 strongly incurved ; the outer large, compressed, sub-spathulate, with obliquely 



t Joimi. M. B. A., N. S., v., 1898, p. 344. 

 % Ann. Ei'p. Port Erin Biol. Stat., 1898, p. 15. 

 2 M 2 



