360 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
complete had it not been for a single haul, no. 7723. This particular 
one was very rich in these small Crustacea and hundreds of specimens 
were picked out from the small amount of the fine sand that was 
examined. Altogether the material from this one station yielded 
nineteen of the twenty-six species found and eight of the eleven genera. 
This one haul gave more species of Ostracods than all the other col¬ 
lecting done during the entire summer. The material from Buzzards 
Bay was dredged by hand from the Department steamer “Phalarope,” 
mostly in much less than ten fathoms, averaging about four to six 
fathoms. These hauls were by no means so rich in Ostracoda as 
those from Vineyard Sound and in the one haul which contained any 
considerable number of specimens, they were all of one species. 
Besides these two sources, material was taken from the Eel Pond 
at Wood’s Hole. This consisted of eel grass, with the mud and other 
material taken with it in the net. By placing this material in open 
dishes the Ostracods could easily be picked out with a pipette. Simi¬ 
lar procedure was made with good results upon material scraped 
from the piles of the wharf at the Station and with eel grass and 
hydroids taken from near the surface in the “Gulf of Canso,” across 
the harbor from the Station. The last locality yielded the only speci¬ 
mens of the Myodocopa seen in the region, with the exception of a 
single specimen from Vineyard Sound, “Fish Hawk” station 7723. 
Periodicity. 
While the work done was almost entirely systematic, one thing 
was incidentally noted which at least suggests an interesting prob¬ 
lem. Among the fresh-water Entomostraca certain species have 
very definite times of appearance and then give way to other species 
later in the season. That similar conditions may take place among 
the marine Ostracoda of the region may be suspected from the follow¬ 
ing casual observations. 
On July 15th, material was collected from the Eel Pond, consist¬ 
ing of eel grass, mud, and other accompanying material. From this 
were obtained many specimens of Loxoconcha impressa and a very 
few of Cytherois zostericola. On August 22d from exactly the same 
part of the Eel Pond, from the same sort of material, and at the same 
hour of the day even, very many specimens of Pontocypris edwardsi 
were taken and not a single specimen of the two species taken in July. 
