1908.] TERRESTRIAL ISOPODS FROM TANGANYIKA. 559 



Fam. Armadillidiid^e. 

 Gen. Periscyphis Gerstaecker. 



1873. Periscyphis Gerstaecker, Die Gliederthier- Fauna des 



Sansibar-Gebietes, van der Decken Exp., p. 526 (Budde- 



Lund). 

 1885. Cercocyton'us Budde-Lnnd, Isopoda terrestria, p. 42. 

 1885. Peryscyphis Budde-Lund, Isopoda terrestria, p. 293. 

 1898. Periscyphis Budde-Liuid, DieLand-Isopoden Ost-Afrikas, 



iv. 3. 

 1908. Veriscyphis Budde-Lund, Swedisli Zool. Exp. in Egypt, 



jS^o. '26 a, p. 10. 



In his latest work Budde-Lund gives a new description of this 

 genus, having recognised that several of the species from German 

 East Africa which he allotted to it in 1898 require a diilerent 

 systematic position. He gives some valuable illustrations of 

 details in his own two species, P. convexus and P. albescens, but 

 the typical species, P. trivialis Gerstaecker, remains untigured. 

 It is obvious that under the new definition those species which 

 have the apex of the telsonic segment quadrate are excluded. 



Periscyphis convexus Budde-Lund. (Plate XXVIL, C.) 



1885. Cercocytonus convexus Budde-Lund, Isopoda terrestria, 

 p. 44. 



1885. Peryscyphis convexus Budde-Lund, Isopoda terrestria, 

 p.' 293. 



1908. Periscyphis convexus Budde-Lund, Swedish Zool. Exp. in 

 Egypt, No. 26 a, pp. 2, 9, pi. 1. figs. 20-25. 



Head with frontal line evanescent in the middle. The side- 

 plates or raised lateral borders of the first perfeon segment 

 broadest where flanking the eyes, narroAving downwards without 

 quite reaching the hind margin of the segment ; the second and 

 third segments narrowly rounded at the lower corners, the 

 following segments more squared, the seventh having the hind 

 margin very concave in the middle but rather flattened at either 

 side. The pleon short, with the segments in position successively 

 shorter in the middle till the telsonic segment, which has a 

 linguiform termination. 



The eyes in our specimens do not appear to have moi'e than 

 20 ocelli. Budde-Lund gives the genus about 25 to 30. 



In the second antennfe the joints of the peduncle in order of 

 length are the 1st, 3rd, 2nd, 4th, 5th, the last decidedly the 

 largest, and longer than the flagellum, of which the first joint is 

 longer than the second. 



The mandibles have a trifid cutting-edge. 



The lobes of the lowei- lip appear to be almost circular. 



The first maxillfe agree closely with Budde-Lund's figures, the 

 inner plate having 2 seta3 or penicils, of which the inner is longer 



Proc. Zool. Soc— 1908, Xo. XXXYI. 36 



