68 Trcnisaclio'ds. — Zoology. ) 



DESCRIPTION OF PLATE X. 



Fig. 1. Lysiosguilla spinosa, Endopodibe of first abdominal appendage 

 of male, posterior side : A, basal joint ; B, terminal joint, 

 with outer lobe a, and imicr lobe b. (Enlarged.) 



Fig. 2. Terminal joint, B, of same, anterior side : d, retinaculum ; e, 

 fixed limb of forceps ; /, movable limb of forceps. Other 

 letters as in fig. 1. (Enlarged.) 



Fig. 3. Portion of the retinaculum, highly magnified, showing the 

 curved seta?. 



Art. VII. — On the Changes in Form of a Parasitic Isopod 



(Nerocila). 



By Chas. Chilton, M.A., B.Sc. 



[Bead before the Otago Institute, 13th October, 1890.] 



Plate XI. 



Nerocila macleayii. 



Gilonera tnacleayii, Leach, MS. ; White, in Dieffeub. Voy, 



N.Z., vol. ii., p. 268. [See Miers, Zool. H.M.S. 



" Alert," p. 301.1 

 Nerocila imbricata, List Crust. Brit. Miis., p. 108, sine 



descr. Miers, Cat. N.Z. Crust., p. 107. 

 Nerocila novcB-zelandice, Schiodte & Meinert, Naturhistorisk 



Tidsski-ifft, ser. iii., vol. xiri., p. 70, pi. v., figs. 10, 11. 

 Nerocila viacleayii, Thomson and Cliilton, Trans. N.Z. Inst., 



vol. xviii., p. 155. 

 Nerocila macleayii, Thomson, Trans. N.Z. Inst., vol. xxi., 



p. 263. 

 This species was given, under the name Nerocila imhricata, 

 in Miers's " Catalogue of the New Zealand Crustacea" (1876), 

 as being represented in the collections of the British Museum 

 by specimens from' New Zealand. Up to the time of publish- 

 ing our " Critical List of the Crustacea Malacostraca of New 

 Zealand " in 1885 neither Mr. Thomson nor myself had met 

 with any specimens, and consequently the note, " We do not 

 know this species," was added in the list after the name of 

 the species. Very soon, however, after the publication of this 

 list both of us got specimens, and it appears that the species 

 is not an uncommon parasite on several fish, especially on the 

 west coast of New Zealand. 



Young forms on which the incubatory pouch has not yet 

 been developed differ very much from the adult female in the 

 proportions of the body, the prominence of the epimera, &c,, 

 so that I did not recognise them as belonging to the same 

 species until I got from the Dunedin Museum a bottle con- 



