Juday—A New Species of Diaptomus. 
803 
A NEW SPECIES OF DIAPTOMUS. 
By Chancey Juday. 
On January 30 and February 1, 1910, some plankton ma¬ 
terial was collected from pools in the vicinity of Puerto Barrios 
and Los Amates, Guatemala. Among the copepods found in 
the collections is a species of Diaptomus which has not been de¬ 
scribed hitherto. The species is named in honor of Doctor C. 
Dwight Marsh in recognition of his valuable work on the North 
American forms of this genus. 
Diaptomus marslii n. sp. 
Male. The cephalothorax is bluntly cone-shaped anteriorly; 
it is widest in the middle. The first segment is about as long 
as the three following ones; the last thoracic segment does not 
have any lateral lobes but has a small spine on either side about 
the middle of the posterior margin. 
The abdomen is elongated and slender, consisting of five seg¬ 
ments besides the furcae. The first segment is short and 
broader than the others; the second is the longest of the five. 
The fourth is asymmetrical, the left side being a little shorter 
than the right; the fifth likewise is asymmetrical, the left side 
being a little longer than the right. The fureal joints are about 
two-thirds as long as the second segment. 
The antennae scarcely reach the anterior ends of the furcal 
rami. The right one is modified for a grasping organ. The 
antepenultimate segment of the right antenna of one specimen 
bears a prominent curved process, but no trace of such a struc¬ 
ture appears on any others (about twenty in all). 
