Pacific Alpheids II — Banner 
191 
Fig. 1 . Map of Arno Atoll, showing collecting stations. Insert : A map of the Marshall Islands, showing the 
location of Arno. 
HABITATS OF THE SHRIMP 
The studies made by Dr. Hiatt include two 
ecological sections of the reef in the extreme 
southern section of the atoll, one on the sea- 
ward and one on the lagoon side. The study 
of the seaward reef was made near the village 
of Ine, in a region quite protected from the 
prevailing winds and surf; that of the lagoon 
reef was made off the islet of Makin, some 
4 miles away. 
The method of taking the transects was the 
same in both cases. A strip 50 feet wide and 
divided into sections, 50 feet long on the 
seaward reef and 100 feet long on the lagoon 
reef, was laid out normal to the shore and 
running from the beach to water beyond 
"skin diving" depth. The animals in each 
section were collected, given field identifica- 
tion and preserved; in the shallow zones this 
was done by wading, in the deeper by "skin 
diving." 
The contours found on both transects were 
about the same, showing a broad, relatively 
flat, gradually sloping reef centering about the 
height of mean low water. An abrupt change 
in slope marked the outer margins of the reef 
flat, with the slope becoming steep on the 
lagoon reef and precipitous on the ocean side. 
