(iatti/ Man'if fjuhoidtory^ St. Ainfrewi. IT* J 



invariiiblc. In the Neapolitiin Salmacina OBdificatrix many 

 s|)ecirnens would seem to show shorter iiiul more sleuder 

 piiiiiie on the Hhimeiits, which throuf^hout are terminated 

 by the tuhir;^(!(l cusliions. 



The higlier Polycluets, as a rule, have the sexes separate, 

 l)ut Filoi/rana is hermaphrodite, and, uioreover, iuereases by 

 aetive bu(hliug, the l)uds rapidly developing sexual elements 

 which may be shed or the ova may l)i; fertilised iuterually 

 and find exit as larvae. All these processes exist, it may be, 

 in (jiie and the same colony, and it is not easy to explain 

 why such diversity should occur, or why sueh characters, if 

 acquired, should not l)e more stable. 



There is little evidence of a struggle for existence in such 

 a form, since the sea supplies at once food and calcareous 

 matter everywhere ; yet the warmer waters appear to favour 

 the development of larger processes at the end of the branchial 

 filaments in certain cases, but this falls under environment 

 rather than individual competition, for it cannot be supposed 

 that the great size of these processes is necessary for the 

 well-being of the species generally. Whilst they may be 

 associated with the environment, yet under the same 

 conditions small terminal processes may be present, just 

 as in colder waters opcrcula may be present or absent 

 in the same colony. In connection with the statement 

 that the warmer waters seem to favour rapid spread of the 

 species it need only be pointed out that, in contrast with 

 the colder eastern waters of Scotland, Filograna flourishes 

 luxuriantly in the genial waters of the Laboratory at Port 

 Erin atid s[)eedily blocks with its calcareous tubes the supply- 

 pipes, whilst on the bouts of Doiigonub in the Red S» a it is 

 equally, if not more, luxuriant. 



Sexual selection would appear to have little or no effect 

 in producing the varieties, though special varieties of opcr- 

 cula or ])ranchiie on a given site may owe their frequence to 

 the ([ualities transmitted by parents, or by the process of 

 budding from a nurse-stock. 



The coloration «'f the branchiae is a feature of moment, 

 especially in connection with the incidence of light. This 

 coloiation is marked in the Australian forn)s and in those 

 from the Red Sea, the Mediterranean, and the south 

 generally, though it is by no means inconspicuous in those 

 of colder climes. Is this coloration protective where it is 

 highly developed, or is it only ornamental? The great 

 beauty, as well as the emlless variety, of the branchial circles 

 or fans of the Serpulids must have struck every marine 

 zoologist, and therein Filixjraiui agrees with its family ; 

 but the [)igment may have special phvsiologieal pur[)oses to 



Ann. <l; Mng. .V. Hist. Scr. 9. Vol. iii. H 



