868 REV. A. M. NORMAN AND MR. G. S. BRADY 



It has been found by G. S. B. in the Loughs at Knarsdale, and 

 in Crag Lough, Northumberland ; in Clearburn Loch, and a pool 

 on Helmoor, Selkirkshire ; on Hilton Pell, Westmorland ; and 

 in bog pools in Connemara : by A. M. N. in Chartners, Aird, and 

 Darden Loughs, and in bog pools near Winters Stob, North- 

 umberland ; and by Mr. D. Robertson in a tarn in the Isle of 

 Cumbrae, N.B. On the Continent it is known in Germany and 

 Scandinavia. 



Genus. ILYOCRYPTUS, G. 0. Sars. 



Carapace somewhat ovate, wider behind than in front, valves 

 separated from each other throughout the greater part of their 

 circumference, ventral and posterior margins fringed with long 

 plumose seta? ; towards the postero-ventral angle these setas gra- 

 dually assume a spine-like character, and themselves bear smaller 

 spines on one side. Anterior antenna? cylindrical, of nearly equal 

 diameter throughout their length; the head is much elevated, 

 and the origin of the anterior antennse is considerably posterior 

 to the position of the eye. Posterior antennse consisting of 

 an immensely developed and very muscular peduncle, and two 

 short rami ; the four-jointed ramus furnished with three terminal, 

 and the three-jointed with five short, geniculate, and plumose 

 setae ; each ramus has at its termination, besides the three setae, 

 a long slender spine, and the second joint of the four-jointed 

 ramus is also furnished with a similar spine. Eye very small ; 

 accompanying eye-spot also small, but large as compared with 

 the minute eye. Abdomen very large and deep, having rows 

 of strong marginal spines, and terminating in two largely deve- 

 loped and very long claws. Intestine not coiled, but dilated, 

 and furnished with a "cylindrical cceciform appendage" (G. 0. S.) 

 near the termination. Ilyocnjptus is unable to swim and drags 

 itself about in the mud at the bottom of lakes and clear pieces of 

 water. 



Ilyocrypttjs sordidus, Lievin. 

 Acantholeberis sordidus, Norman. Ann. Nat. Hist., Ser. 3, Vol. 



