CALLIANASSA. 
CANCER (Astacus). Montagu. 
CALLIANASSA. Leach. 
Antenne in eadem feré linea horizontali insert : 
imteriores pedunculo elongato biarticulato; articulo secundo longiore: sete due: 
superiore sub-compressa. 
exteriores pedunculo elongato ; seta longissima. 
Palpi pediformes articulo secundo compresso longiore. 
Pedes decem: par anticum valdé inequale didactylum compressissimum : par secundum primo 
minus didactylum: par tertium monodactylum : par quartum simplex: par quintum sub- 
didactylum. 
Abdomen submembranaceum. 
Cauda pentaphylla: processus lati; laterales exteriores interioribus majores costati. 
Antenne inserted nearly in the same horizontal line: interior ones with the peduncle two- 
jointed ; the second joint longest: sete two, the upper ones slightly compressed : exterior ones 
with an elongate peduncle and seta. Pedipalpes with the second joint longest, compressed. 
Legs ten: anterior pair very unequal, didactyle, very much compressed: second pair didactyle, 
smaller than the anterior pair: third pair monodactyle : fourth pair simple : fifth pair subdidac- 
tyle. Abdomen somewhat membranaceous. ‘Tail with five broad plates; the exterior ones 
ribbed, larger than the interior lateral ones. 
One species only of this singular Genus has hitherto been observed. It has the same economy 
as Gebra, at least it resides in subterraneous passages of the same construction. 
