ZOOLOGICAL AND BOTANICAL ASSOCIATION. 195 



ornatis ; vix basis longitudinem aequante. Habitat in formicariis. Myr- 

 mica testaceo-pilosa, ad Medea Algeriam in African* {teste M. H. Lucas). 



The affinities of this genus are not so easy of solution as those of the 

 last ; for whilst in the characters of its antennae it approaches somewhat 

 the Philougridae, in those of the telson and its appendages it comes 

 nearer to the Porcellionidae. Unwilling to include in that family a 

 genus having no frontal lobe to the carapace, and the absence of coxae to 

 the first and second abdominal rings, separating it from Philoscidae, for 

 the present I prefer to refer it to the same group as Trichoniscus, which, 

 as I find by examination of the specimens in the Paris Museum, has the 

 same peculiarities. Whether the species to which I refer has been cor- 

 rectly referred by M. H. Lucas, in his "Exploration Scientifique de 

 l'Algeric," to Brandt's genus, it is impossible to tell, as Trichoniscus, 

 like all the genera established in the "Conspectus Oniscodorum, ,, is most 

 imperfectly described ; whilst the species in M. Lucas's work is both de- 

 scribed and figured in detail, and may therefore justly stand for the type 

 of the genus. 



Trichoniscus pusillus of Brandt, the original type species, appears to 

 bo hitherto undescribed, and unfigured, at least under this name. In 

 one respect there is a discrepancy between Brandt's generic description 

 and the species described by M. Lucas — viz., in the characters of the 

 tige of the external antennae, which are thus given by Brandt : — " An- 

 tennae six-jointed, last joint setaceous, penultimate, cylindrical, slen- 

 der." — Conspectus, p. 12. But as Brandt has also, and most incorrectly, 

 as shown in a former part of this paper, included under his Hexarthrica 

 the genus Platyarthrus, he is probably in error here also, especially as 

 in M. Lucas's type specimens of Trichoniscus, which the authorities of 

 the Jardin des Plantes liberally permitted me to examine, I found that 

 the basal joint of the tige was minute, and easily overlooked by the 

 naked eye. I question the existence of an Oniscoid with a single joint 

 only in the tige ; for though such, doubtless, might exist, none is at 

 present known. 



The genus Trichoniscus, as thus established, differs from my new 

 genus Lucasius in having the lateral lobes of carapace less prominent 

 and continuous in front of the orbits, though not prominently so. The 

 form of the body and posterior pleopod resembles Porcellio. The telson 

 approximates that of Lucasius, with which other characters point out a 

 close affinity. 



