BULIMULUS-XAESIOTTJS. 97 



hamensis, a species belonging to a totally distinct group. The name 

 Pelecostoma, therefore, may be safely laid away on the synonymic 

 shelf." 



" The Galapagos Islands, lying under the equator about 90 west 

 of Greenwich, comprise two principal groups separated by nearly 

 1,200 fathoms of water. One of these groups, northwest of the 

 other, contains only Culpepper (550 ft.) and Wenman (830 ft. ele- 

 vation) Islands and a few insignificant rocks. Culpepper, owing 

 to its small elevation, is nearly barren, while Wenman shows on 

 its upper surface a thin coating of grass and other vegetation. From 

 neither of these has any collection been made or is any land shell 

 known. 



"The main group of the Galapagos rests on an elevation of the 

 sea bottom included within the 1,000 fathom line. It may be pro- 

 visionally divided into three groups, a southeastern, a central and a 

 northeastern, in all about a dozen islands and some smaller islets 

 and rocks. 



" The southeastern group comprises Charles, Chatham, Hood ancl 

 Barrington Islands. Hood is destitute of water in the dry season 

 and green only in the wet season, owing to its small elevation which 

 does not bring it into the region of condensing clouds. Much of 

 the surface is covered with blocks of lava. Chatham and Charles 

 are among the most fertile islands of the group. 



" The central islands include the largest of the whole : Albemarle, 

 which appears to consist of several primitive islands united by low 

 areas of volcanic material ; Narborough, which exhibited volcanic 

 activity as late as 1836 ; James ; Indefatigable, and the much 

 smaller Duncan Island, besides a number of islets. Of these, Nar- 

 borough, said to be very fertile, has not been explored at all for 

 land shells. 



" The northeastern group comprises three comparatively small 

 islands, Abingdon, Bindloe and Tower. Three land shells, two of 

 which are Auriculidce, are known from Bindloe; the faunse of 

 Abingdon and Tower being still unknown. 



" The sea currents about the islands and between them and the 

 mainland are very complicated. In a general way it may be said 

 that two currents converge upon the islands, one from an east-north- 

 easterly direction from the Gulf of Panama, and another from a 

 southeasterly direction from the Peruvian coast. Both are strong 

 currents ; both have doubtless contributed their aid in populating; 



