417 
A DESCRIPTION OF SOME GOLD COAST 
ENTOMOSTRACA* 
BY 
W. M. GRAHAM, B.A., M B. 
It is a matter of common observation in the Gold Coast Colony, 
Ashanti and the Northern Territories that the incidence of Guinea 
worm varies locally. Some stations shew a high percentage of cases, 
some a low percentage, and some are free from the disease. \\ hy 
should such local variations exist ? The probable explanation is the 
abundance, the variety or the absence of the Cyclops-host from the 
water sources of the locality. Cyclops belongs to a widely-distributed 
family, and some species of the family can be found readily in the 
water sources of every station. But as Guinea worm disease is not 
present at every station, it is evident that the presence of any species 
in the water is not sufficient to cause the disease. I he inference 
seems probable that a special species of Cyclops is required to act as 
efficient host to the worm, and that the absence of such species from 
the water sources of a station coincides with the absence of Guinea 
worm disease. If this be true, then an exact knowledge of the 
species to be found at each station becomes of great practical 
importance, but there is at present no classification of Gold Coast 
Copepoda. I have, therefore, sought in the present article to furnish 
means for the identification of the species found in the water sources 
°f the station of Obuasi, and in those of the country within a three- 
mile radius round it, as a first instalment. Obuasi is a mining village 
on the Gold Coast Government Railway, 124 miles from Sekondi. 
The country is hilly and covered with forest. During the dry season 
the streams are small, sluggish and full of weed. With the setting in 
the heavy rains thev become rapid torrents, and the weed 
disappears. During the first period, to the end of April, Cyclops 
1 to 5 can be caught in the streams, but after the first week in May 
il •r^ l ' e lhanks of the Editors are herewith given to Dr. Bradv for his kindness in 
' entifving and describing this collection of Entomostraca.—E ds. 
