414 Records of the Indian Museum. [Vol. XXII, 



from one another than are those of the former ; but this is I believe 

 really due to the ground-colour of the carapace between them being 

 darker in one than in the other. 



The shape of the abdomen and the structure of the vulva are 

 also variable. It is perhaps not unlikely that it maj' ultimately be 

 possible to distinguish local races by means of the latter, whose 

 median piece, though always variable, is inclined in Himalayan 

 specimens to be markedly broader than in plains specimens and 

 even obtusely triangular. 



The shape of the abdomen, in spite of its varialjility in 

 detail, is sufficiently constant to afford as a rule a read}' means of 

 distinguishing the present species from other common forms. 



Araneus spp. nr. nauticus, Koch. 

 PI. xix, 1-6. 



All spiders of this series of Simon's third group of the genus 

 appear to be more or less nocturnal, coming out to spin their 

 webs at dusk and leaving them empty bj' day. Males not infre- 

 quently wander into houses in the late evening, presumably when 

 searching for mates, and several were captured thus on Barkuda 

 Island. Several immature specimens were found in their webs 

 among bushes in the jungle after dark, but no adult females have 

 yet been obtained. This is particularly unfortunate as the species 

 are distinguished by the form of the vulva and I have been unable 

 to find any certain means of identifying males or immature speci- 

 mens. The commonest species in the plains seem to be A . nauticus 

 and A. rumpJii, and it is probable that the specimens all belong to 

 one or both of these species.' 



The colouration of this series of spiders varies in a most in- 

 teresting manner. Different species often appear to be charac- 

 terized by different tints ; but closer stud}' seems to indicate that 

 these lints are of local or possibly climatic or even seasonal signi- 

 ficance rather than truly specific. The pattern according to 

 which the colours are arranged appears to be the same for A. 

 nauticus and A. rumfhi and for several Himala5'an and probably 

 other species also ; and the pattern of any one species seems as 

 a rule (though probablj' not always) to be constant. The extent 

 to which the different pigments are developed, however, may 

 vary enormouslj^ making different specimens of one species look 

 far less like each other than like corresponding varieties of allied 

 species. The majority of specimens in all species, except possibly 

 A. masoni which seems always to be dark, are of a marbled 

 greyish or brownish tint. Departures from this normal type are 

 in three main directions: (a) a general reduction of pigmentation, 



' Two mature females have .since been obtained. One at least appears to be 

 A. riimphi. Concerning the other 1 am more doubtful. A careful e.xamination 

 of large series of all species of the group seems to be needed for a full determina- 

 tion of specific characters. 



