39 88 Proceedings of the Royal Irish Academy. 



Discopoma and Uropoda. Auct. The generic characters are briefly as 



follows : — 



Dorsal plates consisting of the usual large shield and two marginal plates 

 which do not cover the posterior margin of the body, resembling the genus 

 Discopoma in this respect. Ambulacra present on all legs, those of the first 

 pair obvious, though smaller than the others. The fossulae pedales are 

 sufficiently well developed, last pair without a separate groove for the 

 reception of the tarsal segments (such as is found in Urodiscella and other 

 genera). Metapodial line present, evanescent towards the middle of the 

 body. Type species, Haluropoda interrupta sp. nov. 



In order to indicate the position of this new genus I have prepared a 

 table based on the characters of the dorsal plates and on the presence, or 

 otherwise, of ambulacra on the first pair of legs. Mr. Michael has published 

 a synoptical table of the then known genera in his " Xotes on the Uropo- 

 dinae " (49, p. 29S), and more recently Berlese compiled a very useful table 

 of the uropodid genera (12. p. 324). "vTith regard to the ambulacra, Michael 

 does not agree that their presence on, or absence from, the first pair of legs is 

 a good method of dividing these genera, though "it may be preserved to 

 differentiate smaller groups," yet it is undoubtedly a useful character, and 

 cannot, in my opinion, be overlooked in the grouping of the genera. 



First pair of legs without ambulacra — 



Marginal shield entire, fused with the central dorsal 

 shield, . . CUliba. {CiUiba.no) von Heyd. 



Marginal shield interrupted, not covering the end of the 

 dorsum . . Discopoma G. et E.CanestrinL 



Marginal shields absent, Pkaidocylliba Berl. 



First pan- of legs furnished with ambulacra — 



Marginal shield interrupted, . . Haluropoda n. gen. 

 Marginal shield entire, . . ' Uropoda Auct. 



Haluropoda interrupta sp. nov. (PI. VII, fig. 28a-c.) 



Male* tig- 2Sf#). — Leiigth866ju to 921^, breadth 716,u. Colour light chestnut, 

 shape sub-discoidal, produced to form the narrow anterior margin. Dorsal 

 shield large, very fiuely punctured with small scattered hairs. The marginal 

 plates are indistinctly punctured, and taper to a point at a little beyond the 



'For the disiinvtire characters of the genera allied to the Uropoda of Auct., see Berlese's table 

 (12 p. 325). They are Cropiitella Berl., Urodiscella Berl., Uroobovella Berl., Urodinychus Berl., 

 and the myrme' ophilous genera, Urutrachytes Berl., and Trachyuropoda Berl. 



