﻿NO. I 



SMITHSONIAN EXPLORATIONS, I925 



45 



In the fourth inclosure had been placed 25 Ccrion incanum and 

 25 Cerion tridcntatum. Of the Cerion incanum, 13, and of the Cerion 

 tridcntatuni, 10, were found dead. Young also were present in the 

 inclosure. 



In the eight smaller inclosures in which had been placed a young 

 specimen of each, Ccriou incanum and Ccrion viarcgis, it was deemed 

 wise not to disturb the vegetation or sand to discover their fate. In 

 some, living individuals were seen ; in others, dead specimens were 

 in evidence. Next year these islets will be examined in detail. 



Fic. 47. — The west shore hue of Loggerliead Key, looking from tlie Aiarine 

 Biological Lahoratory towards the lighthouse. Here many of the marine 



shells found in the region were gathered. 



The colonies whicli were introduced on the top of Fort Jetiferson 

 last year also showed considerable mortality, but a number of living 

 specimens remained. Here too it was deemed best not to disturb the 

 ground, for very young forms have a way of burrowing just beneath 

 the surface of the sand, and exposing them to .sunbght frequently 

 results in killing them. 



This year Dr. Bartsch cut down the large cages made two years 

 ago to the mere four-inch base boards and tops. These were buried 

 a bit around the edge, then a narrow strip of monel wire screening 

 was tacked to the upper edge, allowing about one and one-half inches 

 to project inward. Seventy-five of these inclosures were made, 3x3 

 feet in size. They were provided with the usual plants, and in each 

 4 



