186 



Remarks. — The present genus, established by Mr. Schnitzler, is nearly 

 allied to Porcellio, though in some points, especially in the very convex body and 

 its capability of being rolled up into a nearly perfect ball, it exhibits, as it were, 

 a transition to the next family, the ArmadiUidiidw. Mr. B.-Lund describes 7 

 species of this genus. Of these only a single species is represented in the northern 

 part of Europe. 



Cylistieus eonvexus (De G-eer). . 



(PL LXXXI.) 

 Oniscus conveocus, De Geer, Mem. des Insectes. Vol. VII. p. 553, PI. 35, fig. 11. 

 Syn: Porcellio spinifrons, Brandt. 

 „ „ Icevis, Koch. 



,; „ a/rmadilloides, Leveboullet. 



Specific Characters. — Body oblong oval, more than twice as long as it 

 is broad, side-contours nearly parallel, dorsal face strongly vaulted and perfectly 

 smooth. Cephalon short, transverse, almost 3 times as broad as it is long, lateral 

 lobes rather large, obliquely truncated at the tip, median lobe forming a very 

 small, but distinct acute projection. Side-plates of 1st segment of mesosome 

 very large, partly flanking the cephalon, and acutely produced behind; the succeed- 

 ing pairs with the posterior corner less acute. Metasome not attaining half 

 the length of the mesosome, epimeral plates of the first 2 segments concealed, 

 those of the 3 succeeding segments large, recurved, their lateral margins 

 being continuous with the sides of the mesosome; last segment about as long as 

 it is broad at the base, its terminal part conically pointed, and extending as far 

 as the basal part of the uropoda. Eyes rather large and convex. Antennulse 

 with the last joint about as long as the basal one, and conically pointed. Antennae 

 very slender, considerably exceeding half the length of the body, flagellum a little 

 shorter than the last peduncular joint, and having its 2 articulations subequal 

 in length. Legs moderately slender, and of same structure in the 2 sexes. Inner 

 rami of 1st pair of pleopoda in male with the terminal parts divergent. Uropoda 

 rather large, with the basal part oblong quadrangular, and distinctly keeled along 

 the lower side, outer ramus narrow lanceolate, in male considerably exceeding 

 the basal part in length; inner ramus very narrow, linear, and issuing far in 

 front, thus but slightly projecting beyond the basal part. Colour of dorsal face 

 dark iron grey, with a regular row of light patches along each side of the meso- 

 some, and in each segment a group of less conspicuous flexuous stripes on either 

 side of the median line; uropoda generally ferruginous. Length attaining 12 mm. 



