Ecliiiioilerina II: Crinoidea. 311 



it would appear that this path of migration was interruptod, at least in so 

 tar as its wostorn portioii is coneornod, during, or just subsequent to, 

 Cretacoous timo. 



4. Through the Mediterranean region. At tho time of tlie passage of 

 erinoids from tho ludo-racilic rogion into the Atlantic by way of the 

 Mediterranean, that sea Avas of far greater extent than at present, and 

 reaehed eastward to the Bay of Bengal. This path of migration has long 

 been closed: only two genera of the many which reaehed Europe by this 

 route now survive, both of them being but slightly diftbrentiated from the 

 original Indo-Pacific types from which they took their origin. Of these 

 two genera one inchides only littoral species just as do its eastern aUies, 

 Avhile the other includes species inhabiting water of moderate depth, it too 

 corresponding in this respect to its Indo-Paciüc representative. The former 

 is more plastic than the latter and, though its speciss are strictly littoral, 

 they have collectively a greater ränge than the species of the latter. 



The better known of these genera is Antedon to which all of the common 

 erinoids of the European littoral belong. Antedon occurs throughout the 

 Mediterranean, along the shores of Europe and Africa from Norway to 

 the Gulf of Guinea (including the outlying islands), and also on the 

 American coast from the island of St. Thomas in the Danish West Indies 

 to Rio Janeiro in Brazil, 



The second genus, Leptometra, an oflfshoot of tho widely spread 

 Indo-Pacific Psathyro'm£tra, inhabits the Mediterranean, and in the eastern 

 Atlantic ranges from the Hebrides to the Canary Islands, being found in 

 deeper water than Antedon. 



It is a common thing in discussing the zoögeography of southwestern 

 Europe for authors to assume that at some time the Straits of Gibraltar 

 have been closed, thus affording an entry into Europe for various Clements 

 of the north African fauna. But there are no animals in southern Europe 

 of undoubted African ancestry which cannot reasonably be supposed to 

 have been brought over from Africa by human agency. In this connection 

 the constant communication between the two shores, uninterrupted for 

 centuries, must be borne in mind. In a study of the very earliest works 

 on the West Indies (these dated prior to 1700) one is constantly Struck 

 with the mention of introduced animals and plants from Africa. Even so 

 large a mammal as the camel was established on Ijarbados before 1647, 

 at which time there had also been introduced horses from the Cape Verde 

 Islands and sheep from Guinea. Monkeys (of several species, two of 

 which still survive), Guinea fowl, and hosts of smaller creatures were also 

 21* 



