PROCEEDINGS OF SCIENTIFIC SOCIETIES. 225 
by no means unanimous respecting them. Furthermore, that the question 
is rendered more complicated by the occurrence of a singular gynandro- 
morphous specimen of P. Pollux in the collection of Mr. Semper, of Altona. 
From the evidence given, to admit the conclusion that P. Castor is the male 
of P. Pollua, as has been suggested, we should be obliged to admit not only 
that the female in this species is dimorphic, but also that the same thing 
occurs in the male. Taking all into consideration, Prof. Westwood sum- 
marises and is in favour, 1st, of P. Castor being males of a species whose 
females have not been discovered; 2nd, that the typical P. Pollua are 
females, of which the male with rounded hind wings having a diffused row 
of markings has yet to be discovered; and 8rd, that the coloured figures 
given by the author represent the two sexes of a dimorphic form of the 
species. 
April 1, 1880.—Prof. Atuman, F.R.S., President, in the chair. 
Only two short zoological papers were read, viz. :—‘‘ Description of a 
new Genus of Moth (Pyramocera) of the Family Liparide from Mada- 
gascar,” by Mr. Arthur G. Butler; and “ Notice of Marine Crustaceans 
collected by Mr. P. Geddes at Vera Cruz,” by Mr. Edward J. Miers. The 
Vera Cruz Crustacea include—a female and immature male of a species 
of Panopeus; examples of Pachygrapsus socius, Stimpson, which is very 
probably merely a variety of P. transversus, as it is distinguished only by 
the absence of the dark patch on the immobile finger, which is always 
present in the typical P. transversus ; and a series of females of a species of 
Pinnotheres, possibly the P. angelicus of Lockington. 
April 15, 1880.—The Rev. G. Hrenstow, F.L.S., in the chair. 
Mr. S. A. Wintle (of George Bay, Tasmania) was elected a Fellow of 
the Society. 
The Secretary read a paper, for the Rey. R. Boog Watson, “ On the 
‘Mollusca of the ‘Challenger’ Expedition” (part 5), in which the writer 
observed that temperature, even more than depth, seems an important 
condition in molluscan life, while both prove barriers to distribution, though 
great length of time naturally helps escape from these barriers. Where 
depth and temperature do not check distribution there is no limit to 
universality of distribution, and such is the case with certain existing 
species; still there is no trace of special, lasting and progressive change. 
Mr. Watson has described some thirty-five species, nearly all of which are 
new forms, and belong respectively to the families Solenoconchia, Trochida, 
Rissoellide, Littorinide and Cerithiide. 
Prof. F’. Jeffrey Bell read a note on an abnormal (quadriradiate) specimen 
of Amblypneustes formosus, and afterwards Mr. Charles Stewart exhibited and 
made remarks on another but differently abnormal specimen of the same 
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