14 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 40." 



shores farther north; it is poorer in species, and is modified by the 

 intrusion of a south Australian element, just as has been shown in 

 the case of many other animals. 



Northeast coast. — The northeast coast of Africa is singularly differ- 

 ent in the aspect of its crinoid fauna from the coast to the southward. 

 Of strictly comparable species there are only ten, distributed among 

 eight genera, of which one is not known from farther south; this is : & 



Colobomctra. 



All of the genera are purely East Indian; of the species five extend 

 to India or beyond; these are: 



Heterometra savignii. Dichrometra protectus. 



Stephanometra marginata. Dichrometra palmata. 



Tropiometra encrinus. 



The fauna of northeast Africa therefore is purely a derivative from 

 East Indian stock, just as that of southeast Africa is, but a curious 

 segregation of the genera and species composing the Indo-Pacijic- 

 Japanese region has occurred, one set of forms following the coasts 

 of the Arabian Sea, the other extending in a southeasterly direction 

 toward the Cape. While the faunas of the northeast and of the south- 

 east coasts differ considerably between themselves, they are both 

 about equally related to the general East Indian fauna, and the com- 

 ponent species of both are remarkable in being in general smaller 

 than the corresponding species in the great parent area. 



The shores from Somaliland northward to and including the R6d 

 Sea, and thence eastward to the Persian Gulf, may be considered as 

 marking the Northeast African faunal division. 



Whether or not the genera Antedon and Leptometra reached their 

 present habitat by way of the Arabian Sea— that is, through the 

 fauna now occupying the shores of that basin— it is not possible to 

 say; Mastigometra and Psathyrometra, their eastern equivalents, occur 

 at or near Ceylon, but are known no farther west. They may have 

 gone "overland" from India; may have passed along the shores of 

 the Arabian Sea (or its ancient homologue) and subsequently died 

 out, or, which is much the most likely, they may yet remain to be dis- 

 covered between Ceylon and Suez. 



Summary.— The crinoid fauna of the coasts of Africa falls into five 

 divisions, as follows: 



1. The European division, including the Mediterranean coast, and 

 the northwest coast north of Morocco and Madeira; this falls into two 

 subdivisions: 



(a) The Mediterranean subdivision, comprising the coast of the 

 Mediterranean, and 



(b) The European-Atlantic subdivision, extending on the Atlantic 

 coast from Madeira and Morocco northward; 



