ZOOLOGICAL AND BOTANICAL ASSOCIATION. 189 



Shortly after the communication of this species to me by its disco- 

 verer in England, the Rev. Mr. Hogan, M. H. Lucas showed me, at the 

 Jardin des Plantes in Paris, specimens taken by him at Fontainbleau, 

 with the remark that the species appeared to him to be undescribed. 

 These specimens he had obtained from ants' nests ; he also informed me 

 that in Algeria he had met with an Oniscoid having the same habits, 

 of which he kindly gave me specimens for description, and which I 

 have named Lucasius myrmecophilm (Lucas* sp). 



The singularity of the usual habitat of these animals may well 

 excite attention. It is true that many other isopods are occasionally 

 found in ants' nests. Thus, last month, in the nests of Myrmica rubra, 

 fusca and nigra, at Bray Head, I met Porcellio scab&r, Philoacia mu*- 

 corum, Oniscus fossor, and Armadillium vulgare, but all appeared to be 

 only accidental visitors, not regular denizens, as Platyarthrus is stated 

 to be. On the occasion just noted, I searched upwards of seventy ants' 

 nests, but unsuccessfully, for Platyarthrus Hoffmanmeggii ; the season 

 may have been too late. 



In Brandt's description, given before, the number of articulations in 

 the tige of the external antennae is incorrectly given, but this organ is 

 so often inaccurately described by the older authors, that the discre- 

 pancy need not excite any surprise. 



The affinities of the genus would lead me to place it near Porcellio, 

 from which genus it differs chiefly in the shortness of the external antennae, 

 the shape of the fifth joint of that organ, the remarkable mode in 

 which the posterior pleopods and the telson are articulated together, 

 and in the form of the head. However, I think the genera may very ju- 

 diciously be placed in the same family as I before suggested in my 

 paper, read before the British Association in 1857,* forming, along with 

 Oniscus, Porcellio, and Deto, a well-marked natural family. 



The arrangements of the parts of the head and its lobes are unique 

 in the family, though at first sight obscure, requiring a skilful manipu- 

 lation of the light, &c, to make out ; and in a short notice of this species, 

 communicated by me to the " Zoologist" for 1858, 1 fell into the error of 

 supposing that the same arrangement prevailed here as in Porcellio. The 

 fact is, that in this genus these parts approach more closely in arrange- 



*•* An Analysis of certain allied Genera of Terrestrial Isopoda," Ac, " Nat. Hist. Rev.," 

 vol. iv., Proc. of Soc., p. 274, et seq. 



