727 



THE RKCENT CRINOIDS OF AUSTRALIA — CLAHK. 683 



from the main line across Russia, gradually adapting themselves 

 to the conditions obtaining in the comparatively rigorous north ; 

 with the closing of the sea connection behind them these genera, 

 Heliometra and Hathrometra — at the present time still closely 

 related to their parent East Indian genera Cyclometra and Tri- 

 choinetra — became fixed as an Arctic fauna, and as such survive 

 to-day. 



Besides this open sea connection with Europe and with the 

 Arctic Ocean, certain land connections (not necessarily above 

 the surface of the sea) are unmistakably indicated by the recent 

 Crinoids. 



The adaptable genus Cyclometra, in addition to sending a 

 branch to the northv^^ard, sent one southward from Australia 

 which became acclimated and took on much the same characters 

 as the northern branch, differing in almost the same way from 

 the parent stock. This formed what T have previously considered 

 as the Antarctic species group of Heliometra, but which I now 

 think it would be better to I'ecognize as a separate genus under 

 the name of Solaiiometra (with the genotype Antedon antarctica,. 

 P. H. C), and also, by a meristic variation resulting in the 

 doubling of all the radials and the consequent possession of 

 twenty instead of ten arms, Promachocri'uus. At this time 

 southern South America was connected with the Antarctic land,, 

 and thus Solanometra obtained a foothold on the western coast 

 of that continent. Finding no barriers to its dispersal, it spread 

 rapidly northward, dipping downward when passing under the 

 tropics (not here recorded from water shallower than 286 fathoms) 

 and reaching the Aleutian Islands, Kamchatka, and North- 

 eastern Japan. 



There was also a land sti'etching from southern India south- 

 westward to Madagascar by which the Ciinoids reached South- 

 eastern Africa ; there was no southern portion of Africa, but the 

 Crinoids followed the southern boundary of a land wnich reached, 

 in a general way, from southern British East Africa to Morocco 

 (or some point in northern West Africa) and thence to and 

 including the West Indies, the coast highlands of Venezuela and 

 Columbia, southern Central America, and possibly the Galapagos 

 Islands. 



A few innovations in classification have been incorporated in 

 this Report which seem to be called for by recent accessions to 

 our knowledge. The family Tropiometridje, including the genera 

 TropiomHra, Calometra, Ptilometra, Pteroynetra, and Asterometra, 

 has proved to be quite artificial. It is true that the species of 

 all these genera agree in having the muscles very greatly reduced 

 and the arms ending very abruptly as if broken off, but I find 



