Mr. A. G. Butler on a new Butterfly. 171 
out, producing intercrossings by sexual reproduction. That 
the gemmules of the new form are considerably smaller than 
is usual in Spongilla has little or nothing to do with the 
matter; the gemmules of S. lacustris vary very considerably 
in size in different localities, perhaps according to the size of 
the piece of water inhabited by the sponges, or that of the 
parent animal, but I can say nothing positive as to the cause 
of this phenomenon. 
From what is above stated, we find the gemmules of the 
freshwater sponges adapted in the following manners :— 
1. Passively locomotive with aerostatic apparatus, the flying 
form (of the dry season), nitens series ; 2. Passively locomo- 
tive swimming form, with anchoring apparatus, for propulsion 
at the surface before the wind, /acustris series; 3. Swimming 
form, with check-apparatus for slow locomotion in running 
water, fluviatilis series; 4. Secured from desiccation by a 
double enclosure, adhering firmly to the body of the parent, 
and only arriving at development when the water, during 
the wet season, rises again to the level, genus Parmula, Cart. 
Besides these there also exist freshwater sponges without 
gemmules :—Lubomirskia from Lake Baikal; the forms col- 
lected in the Congo by Dr. Pechuél-Lésche, forming a new 
genus, Potamolepis, a description of which, by myself, has 
lately appeared in the ‘Jenaische Zeitschrift’*, and the subter- 
ranean Spongilla stygia, Joseph, from the Cave of Gurk, in 
Carniolia. 
In conclusion, I repeat my previous request to all my 
fellow-labourers to be kind enough to aid me with material, 
accompanied by the most exact account of the localities (the 
nature of the water, whether moving or quiet, whether 
large or small, brook, river, old river-course, pool or lake; the 
nature of occasional aftluences, whether exposed to desiccation, 
&c. It is necessary to know everything!). A great many 
gentlemen have most kindly complied with my former prayer, 
but for the solution of certain questions the material can 
hardly be large enough ! 
XX.—On a new Genus of Butterfly from New Zealand. 
By Artuur G. BuTLeER, F.L.S., F.Z.8., &e. 
AT a meeting of the Philosophical Institute of Canterbury, 
New Zealand, held on the 30th November, 1883, Mr. R. W. 
Fereday read the “‘ Description of a Species of Butterfly new 
* See Ann. & Mag. Nat. Hist. ser. 5, vol. xii. p. 391, Beene 1833. 
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