THE HELLERIID^ 425 



characters ascribed to them in the preceding family. The 

 first pleopods are absent or reduced to widely separated 

 rudiments, of doubtful homology. The pleopods of the 

 second, third, fourth, and fifth segments are two-branched ; 

 the second pair have the usual stilets in the male. On each 

 opercular plate there is a roundish air-cavity placed near 

 the outer margin, with a single opening in each operculum 

 of the second pleopods, but two openings in those of the 

 three following pairs. According to von Ebner, the pe- 

 duncle in the pleopods forms a part of the branchial sack, 

 so that the two branches instead of being freely articulated 

 with it are fastened direct to the segment. The uropods 

 are similar to those in the Tylidse, but are attached at the 

 front corner of the outer margin instead of at its centre. 

 The minute terminal joint is considered to be the outer 

 branch. 



Helleria, Ebner, 1868, is the only genus, and Helleria 

 hrevicornis^ Ebner, the only species. It occurs in Italy, and 

 in the mountain forests of Corsica in damp moss ; also M. 

 Chevreux has recently sent it me from Cap d'Antibes out 

 of his own garden. In 1879 Budde-Lund changed the 

 name Helleria to iSyspastus, because other genera of Crusta- 

 ceans have received the name Helleria^ but these other 

 genera, as M. Chevreux has pointed out, were named not 

 before but after the publication of von Ebner's genus. It 

 would be absurd that Dr. Camil Heller should be entirely 

 deprived of the honour intended him. through the fact that 

 so many of his friends had separately endeavoured to render 

 it. Without question von Ebner's genus must retain its 

 original name, and, with the cancelling of 8yspastus, Budde- 

 Lund's family ' Syspasti ' naturally suffers a corresponding 

 change into Helleriidse. The figures on Plate XIX. are 

 copied from von Ebner's paper. 



Family 4. — Oniscidoe. 



The animal is seldom very convex or capable of easily 

 assuming a globular form. ' The head is little broader than 

 long, and not clearly flanked by the first segment of the 



