172 



ramus narrow lanceolate, and exceeding the basal part in length, inner ramus 

 narrow linear, and extending to about the middle of the outer. Colour of dorsal 

 face in adult specimens dark chocolate, with a regular row of whitish patches 

 along each side of mesosome, at the base of the side-plates, and a few small, 

 opaque white dots nearer the median line. Length of adult female reaching 1 6 mm. 



Remarks. — There seems not to be sufficient reason for rejecting the 

 specific name aselliis assigned to this form by Linnaeus. It may be that he con- 

 founded several species under this name, but a similar case undoubtedly concerns 

 also many others of the Linnean names now generally adopted. The specific 

 name more generally used for this species is that proposed by Cuvier, viz., mu- 

 rarius. The Oniscus fossor of Koch is scarcely different from this species, the 

 characters assigned to this form being such as pretty well apply to younger 

 specimens of Oniscus asellus, which are generally of a duller appearance, with 

 the dorsal face more roughly granulated than in adult animals. 



Occurence. — This is one of our most common Oniscoida, occurring often 

 in great abundance, especially in the immediate vicinity of towns. In Christiania I 

 have taken it very plentifully around the ramparts of Akershus, especially beneath 

 old tiles, where often hundreds of them may be found associated. It is also very 

 common in the hot-houses of the Botanical Garden. It has also been col- 

 lected at Drobak, Skien, Brevig, Langesund, Kragero, and Grimstad, and conser- 

 vator Storm states that it occurs plentifully in the vicinity of Trondhjem. It is 

 not particularly rapid in its motions, though it runs away at once, when disturbed, 

 to conceal itself. 



Distribution. — Sweden, Denmark, Germany, Holland, Britain, France, 

 Spain, Italy, Azores, Iceland, Greenland, North America. 



Gen. 2. PhllOSCia, Latreille, 1804. 



Generic Characters. — Body oval, slightly convex, with rather thin integu- 

 ments. Cephalon rounded in front, without any projecting lateral lobes. Side- 

 plates of mesosome but slightly prominent. Metasome abruptly contracted, with 

 the epimeral plates small and appressed ; last segment not much produced. Eyes 

 well developed, lateral. Antennse very slender, with the flagellum composed of 

 3 articulations. Mandibles with only a single penicil behind the cutting part. 

 Legs very slender and greatly increasing in length posteriorly. Opercular plates 



