Messrs Leslie <&; Herdman on Tiwertehrata of Firth of Forth. 201 



refer to some of our own species, whicli are " keepers at home," 

 where no formidable physical features intervene to narrow 

 their range. The reddish-grey bat (F. nattereri) confines 

 itself to a very limited area, and the serotine ( V. serotinus) 

 limits its flight to the neighbourhood of London. True, some 

 of the bats are almost cosmopolitan. The large fox bat 

 {Xantharpia mgyptica) ranges from Egypt and Palestine to 

 Southern India. In conclusion it was asked, — Can the 

 migration of mammals be studied to any profit without some 

 knowledge of the area of their former general distribution ? 

 Have we data to warrant the temperature theory, and, so far 

 as we have, what is their value ? Is it not likely, from facts 

 that have been given in this paper, that the territorial limits 

 of the present migrations of mammals were once held by their 

 ancestors throughout the year ? Can we explain the pheno- 

 mena of periodic migrations, except on the hypothesis that an 

 inherited memory of ancestral home occasionally becomes 

 active, and impells towards it? "These questions," it was 

 added, " show my unwillingness to dogmatise. My scientific 

 conviction, however, is, that while far too much weight has 

 been given to climate, especially in accounting for the migra- 

 tions of mammals, the hypothesis, warranted by many facts, 

 of a hereditary drawing towards, mayhap, even the extreme 

 limits of the area of original distribution, has been much, if 

 not altogether, ignored in the literature of this interesting 

 though difficult subject." 



Xll. The Invertebrate Fauna of the Firth of Forth. By 

 George Leslie, Esq., Demonstrator of Zoology, Uni- 

 versity of Edinburgh; and W. A. Herdman, Esq., 

 D.Sc, F.L.S. Part II., Comprising the Protozoa, 

 PoLYZOA, Crustacea, and Tunicata. 



(Read 20th April 1881.) 



FEOTOZOA, 



In this list the Foraminifera only are catalogued, the 

 other Protozoan groups being omitted for the present, as 



