334 PROCIOEDINGS OF THE ACADEMY OF [1890. 



Echinometra subangnlaris, West Indies, Charleston, S. C. to Des- 

 terro, Brazil. 



Toxopneustes variegatus, West Indies, Beaufort, N. C. to Armayiio, 

 Brazil. 



Mellita pejifapora, West Indies, Cape Hatteras to Itahapuana, 

 Brazil. 



Thyraster serpentarius, Vera Cruz. 



Echinaster Brasiliensis, West Indites, Florida Channel to Rio 

 Janeiro. 



Astropecten articulatns, West Indies, Beaufort, N. C. to off Jolho, 

 off the N. E. coast of Yucatan. 



Luidia alternata, West Indies, Florida to Bahia, Brazil. 



Ophiura cinerea, West Indies, Florida Reefs to Abrolhos Islands. 



Ophiothrix an.gulata, West Indies, Beaufort, N. C. to Rio Janeiro. 



It will be observed that with the exception of the Holothurians, 

 and Thyraster serpentarius, the Echinoderms obtained are all common 

 to the West Indies, and their method of distribution points to this 

 region as their center of propagation. Four of them have a longitu- 

 dinal range of about 4,000 miles, extending approximately from Cape 

 Hatteras in the north to Santa Catharina in the south. The others 

 have a more limited range, one extending from the Florida channel 

 to Rio Janeiro, two from Florida to Bahia, one from Florida to 

 Fernando de Noronha, and one is only known as yet from Vera 

 Cruz. A range is thus indicated, comprehending all the species 

 referred to, limited by Cape Hatteras in the north, and the is- 

 land of Santa Catharina, off the southern portion of Brazil, in the 

 south. These northern and southern limits represent points crossed 

 by the isotherms of 15° C. (60° Fahr.) in both hemispheres dur- 

 ing the coldest month of the year. South and north of these local- 

 ities respectively the surface temperature of the water never 

 falls below this degree of warmth. Of the five littoral species of 

 Echini, however, recorded by Professor Alexander Agassiz from Cape 

 Dos Bahias, Patagonia, in his Report upon the Echini of the Has- 

 sler Expedition, two belong to the We.st Indian fauna. The question 

 is thus raised of the true southern limit of the West Indian fiiuna. 



The localized habitat of the Holothurians collected is in striking 

 contrast to the broad ranges of the other species. This localization 

 is largely characteristic of the shallow water Holothuroidea. The 

 greater number of known species are confined either to one locality 

 or to a very circumscribed area. This fact was illustrated by the 



