420 Rev. A. M. Norman on Ligidium agile, Persoon. 



with reference to the genus Philoscta : — " It is a curious cir- 

 cumstance that the animals of this genus, common as they are, 

 and well described by Latreille and Zaddach, should have been 

 unknown to Brandt, Lereboullet, and Milne-Edwards, who 

 have affirmed that the genus ought to be re-united to Oniscus, 

 whereas it is in fact more nearly allied in several respects to 

 Ligia. The typical species appears to have been figured by 

 Koch under the name of Ligia melanocephalaj which in his 

 generic table he subsequently altered into the generic name of 

 -^/a, giving, however, fifteen joints to the antennas, the flagellum 

 being represented as composed of ten articulations." 



Now, while the authors to whom Spence Bate and Westwood 

 refer were undoubtedly wrong in mistaking a certain species of 

 Oniscus for the genus Pkiloscia, Bate and Westwood have 

 themselves fallen into as serious an error in merging Zia, v/ith 

 its fifteen-jointed antenna and other strongly marked characters, 

 with Philoscia. The genus Zia of Koch is synonymous with 

 the previously described genus Ligidium^ Brandt ; and our 

 recently discovered British Crustacean is the typical species, 

 the Ligidium Persooni, Brandt, the specific name of which 

 must, however, yield to the prior appellation of Persoon him- 

 self, and the Oniscoid must bear the name of Ligidium agile 

 (Persoon). 



Mr. Stebbing's Avoodcut is very characteristic, and agrees 

 very closely with the admirable figures of Lereboullet. 



The following is the complete synonymy of the species as far 

 as it is known to me. As here in the country I have no means 

 of referring to such Avorks as are not in my own library, I am 

 unable personally to verify four of the references, namely those 

 to Koch, Panzer, Brandt, and Cuvier, the first of which I quote 

 on the authority of Budde-Lund in his 'Danmarks Isopode 

 Landkrebsdyr,' and the last three on the authority of Lere- 

 boullet. Zaddach gives Zia meJanocepliala^ Koch, as a syno- 

 nym, and adds ''Zia paludicola et Zia agiUs^ quas Koch 

 describit, varietates tantum hujus speciei esse videntur." 



Ligidium agile (Persoon). 



Oniscus ar/ilis, Persoon ; Panzer, Faun. Germ. fasc. ix. fig. 24, 



Oniscus hi/pfiormn, Cuvier, Jom*n. d'llist. Nat. vol. ii. p. 19, pi. xxvi. 

 figs. S-5 ; Fabricius, Syst. Entoni. Suppl. p. 300. 



Lif/ia hypnorum, Latreille, Gen. Crust, et Insect, vol. i. p. 08, Hist. Nat. 

 des Crust, et Insect, vol. vii. p. 51 ; Bosc (edit. Desmarest), Hist. Nat. 

 des Crust, vol. ii. p. 179 ; Desmarest, Consid. Gen. sur la Classe des 

 Crust, p. 318 ; Lucas, Hist. Nat. des Crust, p. 263. 



Li/fj/idiinn Persooni, Brandt, Conspectus Crust. Onisc. p. 174; Milne- 

 Edwards, Hist. Nat. des Crust, vol. iii. p. 158; Lereboullet, Mem. 

 sur les Cloportides^ p. 14, pi. i. fig. 1, & pi. ii. figs. 20-31 ; Johnsson, 



