Juday—Lakes in Central America. 
237 
Copepods and their nanplii were found at all depths, but 
“they were most abundant in the 0-5 m. stratum. Diaptomus 
was more abundant than Cyclops in the upper 10 m., but below 
this depth the latter was more abundant. 
The cladocera were represented by Daphnia longispina var. 
Lyalina, Ceriodaphnia pulchella, Ceriodaphnia lacustris, and 
Bosmina longirostris. The first three forms were present at all 
depths, but Bosmina was confined to the upper 20 m. Daphnia 
was more aboundant than the other three cladocera and they 
all reached their maximum numbers in the 0-5 m. stratum. 
Lake Atitlan.—The phytoplankton was very abundant in this 
lake but consisted almost entirely of Melosira gramdata. This 
form was most numerous in the upper 15 m. where the average 
number was more than 46 million per cubic meter. A few 
specimens of Gloeocapsa and Zygnema were found in the upper 
15 m. 
Four rotifers were found in the catches, Polyarthra platyp- 
iera, Anuraea stipitata, Brachionus pala, and a Bdelloid form. 
Polyarthra was noted in only one catch, that made in the 5-15 
m. layer. Anuraea was found only between 5 m. and 30 m. 
Brachionus was by far the most abundant rotifer and was pres¬ 
ent in the catches from all depths. The maximum number was 
in the catch from the 15-30 m. stratum. This form was also 
found in considerable numbers in the littoral as well as in the 
limnetic region. A very few specimens of a Bdelloid rotifer 
were noted. 
Cyclops was the only copepod noted in the catches from 
lake Atitlan. It did not occupy the 0-5 m. stratum but was 
present at all other depths. It was most abundant between 5 m. 
and 30 m. The nauplii were distributed from surface to bottom 
but they, too, reached their maximum number between 5 m. 
and 30 m. 
Five cladocerans were found in the catches, namely Daphnia 
longispina var. hyalina, Daphnia pulex, Diaphanospma brach- 
yurum, Ceriodaphnia pulchella, and Bosmina obtusirostris. 
All were absent from the 0-5 m. stratum and D. pidex was not 
noted in the upper 100 m. Both Diaphanosoma and Ceriodaph¬ 
nia were confined to the upper strata as in temperate lakes in 
summer; they were found only between 5 m. and 15 m. Both 
Daphnia hyalina and Bosmina were present in all catches be¬ 
low 5 m., but they were most numerous between 5 m. and 15 m. 
