new Crustacea from Devon and Cornwall. 297 



contrary, of a dense uniform purple or ruby colour. It 

 measures about 1-3 mm. {^ of an incli) in length. The 

 rostrum truncated, not much produced, the truncated end 

 being obscurely tridentate. 



Antennules short, stout, and six-jointed; first three joints 

 subequal and about twice the entire length of the last three, 

 the penultimate joint being very small ; antennae and mouth- 

 organs as in 1\ purinireum. 



The first pair of swimming-feet resemble those of the same 

 species, but the first and second joints of tiie outer branches 

 are of nearly equal length ; they each bear a short seta near 

 the middle of the outer margin and a similar seta near the 

 distal end of the inner margin; the end joint is very skort 

 and furnished with three claws (two stout and of moderate 

 length and one short) and a small seta. The inner branches 

 are stout and composed of two joints; a seta springs from 

 the distal end of the inner margins of the first and second 

 joints, but the second joint is also furnished with two a[)ical 

 setae. The second, third, and fourth pairs are apparently 

 similar to those of P. purpia-eum. In the fifth pair the 

 primary joint appears to be sliort and bears one seta on the 

 outside and two on the inside dist;il angles ; the second joint 

 is also short and provided with six stout plumose setaj on the 

 lower half of the outer margin and apex. 



The first segment of the abdomen forms a trilobed plate 

 which entirely overlaps the remaining abdominal segments 

 and furcal joints, and in this respect differs very markedly 

 from other described species ; in these the last abdominal 

 segment and furcal joints are exposed. 



Genus Mesocheres, nov. 



Body somewhat similar in general appearance to Scotto- 

 cheres, Giesb., the cephalothorax seen from above being ovate 

 in outline, while the abdomen is narrow and elongated. The 

 antennules are composed of twenty-one joints and are similar 

 in structure to those of Aslerocheres, The antennae also 

 resemble those in the same genus. The mandibles and 

 maxillae were damaged and could not be satisfactorily made 

 out. The first maxillipeds are small but moderately stout, 

 their terminal claws elongated and strongly hooked and with 

 an elongated spine attached near the base of the claw. Second 

 maxillipeds long and slender, and similar in structure to the 

 same appendages in Aslerocheres. First four pairs of 

 twimniing-feet somewhat similar to those of the same genus. 

 Fiith pair very small and apparently two-jointed. 

 Ann. (& Mag. N. Hist. Ser. 7. Vol. xv. 21 



