CRUSTACEA FROM EAST COAST OF SCOTLAND 153 
the “Tenth Annual Report of the Fishery Board for 
Scotland ” (1892). 
Lichomolgus arenicolus appears to be a rare species. 
Some important. details of structure not noticed in “ British 
Copepoda” are here described and figured, as are also 
several others, to illustrate the description of the species, 
viz.: the posterior antenna with its remarkably articulated 
and clawed terminal spines, the rudimentary female pos- 
terior foot-jaw, and the fourth pair of swimming-feet, which, 
like the other three pairs, has both branches three-jointed, 
and which in this respect forms, with Lzchomolgus aberdon- 
ensts, Lichomolgus littoralis, and Lichomologus sabelle, a 
distinct group——the other species of Lzchomolgus being 
distmeuished from these three by ‘having the. inner 
branches of the fourth pair of swimming -feet one- or 
two-jointed. The one- or two-jointed inner branches of 
Micmieuney pair of feet constitute one of the characters 
of the genus Lzchomolgus, while a second character is that 
of the mandible, which has the form of “a slender stylet, 
dilated at the base, but excessively slender and filiform 
beyond the middle.” In Lzchomolgus arenicolus there are 
two mandibular stylets, and in Lzchomolgus aberdonensis and 
littoralis the mandible, which is moderately stout and broad, 
hacemomstylers, but is armed at the extremity with one or 
two tooth-like processes and a few sete. In consequence of 
ius) Giversemce’ irom some of the generic characters of 
Lichomolgus, it may become necessary to institute one, or 
possibly two, sub-genera for the reception of these aberrant 
iopmmiom On otnernwise. to alter the @enerie definition sof 
Lichomolgus so as to include them. 
Should it be found desirable, for the reasons stated, to 
remove Lichomolgus littoralis and aberdonensis into a different 
genus or sub-genus, we would suggest - Platycheiron as an 
appropriate generic name,—being descoptive of the remark- 
ably broad ultimate joint of the male posterior foot-jaws 
of the two species referred to. 
1 A species described by I. C. Thompson in ‘‘ Proc. Liverpool Biol. Soc.,” vol. 
iil. p. 68. He also records Z. albens, Thorell, from Liverpool Bay, but we have not 
as yet seen any description of this species. Another species (apparently new), 
having the inner branches of the first four pairs of swimming-feet three-jointed, 
has just been obtained by us, and will be described and figured later. 
