BIGELOW: COAST WATER EXPLORATION OF 1913. 333 
Barnegat (Stations 10060 to 10068); but it was absent at the more 
southern stations, nor was it found over the outer part of the shelf 
south of Long Island (Stations 10063, 10065). And tripos invariably 
outnumbered it in the hauls south and west of Cape Cod. On our 
coasts, at least in summer, longipes evidently belongs to northern water. 
The salinity in which it was living (on the surface, where all the hauls 
with the * 20 silk net were made) ranged from 31.8%o (Station 10104) 
to 33.4%p (Station 10061); the temperature from 48° (Station 10095) 
to 69° (Station 10069). But it was far less abundant at temperatures 
above 62° or 63° than in the colder water of the Gulf:— for example 
at Station 10061, surface temperature 68°, only two specimens were 
detected; Station 10062, 67°, only an occasional SpEaMEN Station 
10069, 69°, only one specimen was found. 
: Discerbinue trupos was taken at practically all our Soieen stations, 
as well as north and east of New York and in the Gulf of Maine, and 
at Stations 10063, 10065 over the outer part of the shelf where longipes 
was absent. At only three Stations have I failed to find it in the 
plankton, viz., 10075, 10076, 10078, all of them within the influence 
of Chesapeake Bay water (p. 200). 
A third species of Ceratium, C’. macroceros, easily distinguished by its 
very long, slender horns, occurred in the hauls at the southern stations. 
The most northerly records are Stations 10062, 10063, and 10083. 
| East of Barnegat it was greatly outnumbered by tripos (Stations 10062, 
| 10063, 10065, 10067, 10069, 10083). South.of this, where longipes was 
not found, macroceros was always as numerous as trzpos, the two species 
being, roughly, equal at Stations 10073, 10074, 10077, 10079, 10082. 
At Stations 10070, 10071, 10072, macroceros outnumbered tripos. 
Ceratiwm macroceros was living at a very wide range of salinity, as 
| much so, even, astrzpos (31.3% to 35.2%); butits temperature range 
| was considerably less, the records all being from water warmer than 
63° (63° to 77°); it was only once found in water cooler than 67°, and 
_then only an occasional specimen (Station 10067). And at only three 
Stations (10062, 10067, 10069) were both longipes and macroceros taken 
in the same haul. If the former belongs to boreal plankton, the lat- 
| ter is as certainly limited to warm water along our coasts. 
| A fourth species of Ceratium, C. fusus, plays a subordinate réle. 
It has been found at twenty-seven stations, including the Gulf of 
Maine as a whole (Stations 10057, 10058, 10086-10090, 10092, 10093, 
be 10097, 10099, 10102-10104), and the continental shelf south 
and west of Cape Cod (Stations 10061-10063; 10067-10070; 10073, 
10074, 10077-10081). The only regions where it was notably absent 
were in the Gulf Stream water (Station 10071); and in localities 
: 
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