G68 MR. E. J. MIERS ON A COLLECTION OF [JuUe 19, 



joint of the uropoda in situ. One, which is loose in the tube, and 

 almost certainly belongs to this species, is short, barely twice the 

 length of the basal joint. 



As the external antennae are wanting, it must be a matter of un- 

 certainty whether this species is to be referred to this genus or 

 Oniscus. 



The Porcellio spinicornis and Porcellio nigra of Say (Journ. Ac 

 Nat. Sci. Phil. i. pp. 431, 432, 1818), from the United States, belong 

 to this subgenus, as specimens in the British- Museum collection 

 presented by Say, prove. In both species the body is more closely 

 articulated, and the terminal segment more triangular and shorter 

 than in P. cayennensis. 



Subgenus Porcellionides. 



Postero-kteral angles of the first four segments of the body not 

 acute and not produced backward. 



a. Depressed, with the antero-lateral portion of the head small. 

 Porcellio jelskii, sp. n. (Plate LXVIII. fig. 3.) 



Oblong-oval, depressed, very finely and closely punctulated, and 

 with scattered but faintly indicated granules, tending to a trans- 

 verse arrangement on each segment. Head small, transverse ; antero- 

 lateral lobes very small, nearly obsolete. Eyes small, black. First 

 four segments of the body with the posterior margins straight, and 

 forming nearly a right angle with the lateral margins ; remaining 

 segments with the posterior margins becoming successively slightly 

 more excavated and with the postero-lateral angles subacute. Tail 

 short ; third to fifth segments with the posterior margins straight to 

 within a short distance of the postero-lateral angle, which is acute, 

 and directed backwards ; terminal segment triangular, rather broader 

 than long, with a slight depression above, with the lateral margins a 

 little excavated, subacute at the extrem.ity, and projecting but very 

 sliglitly beyond the basal joint of the uropoda. Antennae slender, 

 with the two terminal joints (flagellum) together about as long as 

 the preceding, the terminal a very little shorter than the penulti- 

 mate joint. Uropoda with the terminal joint two or three times as 

 long as the preceding, narrow-lanceolate, acute at the extremity. 

 Colour light purplish- brown, variegated with irregular narrow pale 

 markings ; lateral margins of the segments without broad yellow 

 bands. Length 5 lines, breadth 2 lines. 



Hub. Peru ; Guiana. 



A large series of specimens of this species, which appears to be 

 common, is in the collection. 



This species differs from P. chilensis, Dana (nee Gay), in the 

 joints of the flagellum of the external antennae (in that species the 

 first is nearly twice the length of the second joint), the more deeply 

 concave seventh segment of the body, and the longer rami of the 

 uropoda — from P. cubensis and P. sumichrasti, De Saussure, from 

 Cuba (which it somewhat resembles in the form of the terminal 



