v-3 



INTRODUCTION. 



XCV 



autumn of 1859 for the express purpose of endeavouring 

 to ascertain the nature of this submarine deposit. The 

 result of these researches was recorded by Mr. Hyndman 

 in the ' Reports of the British Association ' for 1857 and 

 1858 ; and some observations on the same subject by 

 Mr. Waller will be found in the ' Journal of the Royal 

 Dublin Society ' for 1858 (vol. ii. p. 29-34), as well as by 

 myself in the ' Annals and Magazine of Natural History ' 

 for August 1858 and February and September 1859. The 

 association or collection in the same spot of forms which 

 have been usually regarded as Northern and Southern is 

 one of the most peculiar features of this inquiry. Colum- 

 bella Holbollii, Scalaria (?) Eschrichti, Natica clausa, 

 Margarita cinerea, and Trophon Scalariformis (all of 

 which are decidedly " Arctic " species), Crania anomala, 

 Trichotropis borealis, and Puncturella Noachina (which 

 were regarded by Forbes and Hanley as " boreal " types), 

 Terebratula caputserpentis, Lima subauriculata, and Fis- 

 surella reticulata (being, according to the same authors, 

 " Atlantic "), Argiope cistellula, Trochus Montagui, and 

 Pecten tigrinus (" British "), Astarte sulcata, Buccinum 

 undatum, and Venus Casina (" Celtic "), Artemis lincta, 

 Corbula nucleus, and Trochus cinerarius (" European "), 

 together with Bissoa striatula ("Lusitanian"), all of 

 them in the same fresh and apparently recent condition 

 and (with the exception of those included in the first and 

 last categories) in a living state, were congregated to- 

 gether in this locality, as if on purpose to refute certain 

 theories of geographical distribution. With respect to 

 those species which were not taken there in a living 

 state, it was surmised that they were fossil, or had been 

 carried to the spot by marine currents. Some of the 

 specimens in question I submitted to Dr. Carpenter, 

 whose researches on the microscopical structure of mol- 



