NORMAN ON THE GENUS MYSIS yy it 
more than half the length of the fourth.’ Mysis Helleri, 
Sars, a Mediterranean species also found at the Channel 
Islands and on the coast of Devon, is very like in general 
character to Mysis spiritus, from which, Norman observes, 
it may be at once distinguished by the very short and 
nodulously swollen first articulation of the subdivided sixth 
joint in the trunk-legs. Mysis Lamorne, Couch, has the 
telson deeply but narrowly cleft. Mysis arenosa, Sars, is 
a small species in which the pleon is shorter than usual, 
the eyes are short, the fourth pleopods of the male do nat 
reach the apex of the telson, the incision in the telson is 
about one-fourth of its length. This species, first described 
from the Mediterranean, has since been found in South 
Devon and in Scotland. Thus nine species of the genus 
have been assigned to the British Fauna. In the ‘ Annals 
and Magazine of Natural History’ for September, 1892, 
Canon Norman has distributed these species among four 
genera, in which the distinctions depend chiefly upon the 
remarkable and varied modifications of the pleopods in the 
male sex, and upon the form of the antennal scale. Under 
this arrangement the species flewuosus, neglecta, and inermis, 
are referred to Macromysis ; spiritus, ornata (including ‘Ker- 
viller), arenosa, Helleri, and Parkeri, to Schistomysis ; and 
vulgaris to Neomysis. Mysis Lamorne is transferred to 
ITemimysis. As already observed, for Macromysis must be 
substituted the older name Praunus. The species Parkeri, 
Norman, 1892, from South Devon, is a new one. It is 
very uear to Schistomysis spiritus, from which it may be 
distinguished by the more twisted and bent inner uropod, 
armed with about fifteen spines on the inner margin, 
increasing in size from the base of the appendage. In 
Schistomysis the antennal scale is sub-rhomboidal, with 
the apex greatly produced beyond the spine of the unviliated 
external margin; in Neomysis this scale is ciliated on both 
margins, and runs out to a spine-like apex. The species 
Thenusto longispinosa, Goodsir, and Themisto brevispinosa, 
Goodsir, from the Firth of Forth, are evidently male forms 
of the genus Mysis, but their specific identity has not been 
determined. The generic name Themisto is preoccupied. 
