Rotatoria B13 
Diurella collaris (Rousselet). 
Collected by Jessup from lakes on Old Crow river flats, 40 miles north of 
New Rampart House, on July 3, 1911. 
Diurella cavia (Gosse). 
A few specimens in Jessup’s collections from a pond near New Rampart 
House, at the International Boundary and Porcupine river, on June 12, 1911. 
FAMILY SYNCHATIDA. 
Synchaeta oblonga Ehrenberg. 
Abundant in collections made from the lake at Bernard harbour by Johansen 
on May 6 and 7, 1916; same lake south of Bernard harbour, May 21, 1916. 
Synchaeta johanseni, new species. 
Plate 1, fig. 3. 
The body is fairly slender, bell-shaped and very transparent. Its greatest 
width, about mid-length, is one third of the total length. The foot is well 
marked off from the body, large at the base and tapers gradually to the very 
small toes; its length is one fourth of the length of the body. The head is tri- 
angular and the auricles powerful; on the median line, between the anterior 
pair of tactile bristles, there is a tubular sensory organ as in S. vorax Rousselet. 
The dorsal antenna is in the normal position; the lateral antennae are near the 
posterior end of the body and well towards the ventral side; they are slender 
tubules, armed with a minute tuft of setae. The foot glands are very small. 
The one and position of the eyespot could not be made out from the preserved 
material. 
Total length 350 »; width of body at mid-length 120; length of foot 
70 w; length of toes 7 u. 
This species occurred in large numbers in a surface collection made by F. 
Johansen on August 23, 1914, at station 36, off Cape Lyon, in Amundsen gulf. 
Synchaeta johanseni is closely related to S. vorax Rousselet, from which it 
differs in the more slender body, longer and stouter foot, very small foot glands 
and minute toes, as well as in the position of the lateral antennae. Its presence 
in Amundsen Gulf is of the greatest interest, as up to the present only two species 
of rotifers, Synchaeta atlantica and Trichocerca (= Rattulus) hensent, are known 
from oceanic waters; these were both found by Zelinka in the collections of the 
German Plankton Expedition from the Atlantic ocean, south of Iceland. While 
it would perhaps be incorrect to call Amundsen Gulf an ocean, the conditions 
where the collection was made are oceanic, at least as far as salinity and absence 
of admixture of fresh water are concerned; there are no rivers of any consider- 
able volume discharging near Cape Lyon, and Mr. Johansen informs me that 
few of the rivers flowing into the Arctic ocean carry much water in the summer. 
How to account for the presence of this rotifer at a single station and its absence 
everywhere else is a problem for which no solution can be offered; it may be 
noted that the collection contained virtually no other zodplankton, and it is 
possible that the absence of enemies may be an important factor in the mains 
tenance of this rotifer in such a circumscribed area. 
Filinia longiseta (Ehrenberg). 
Triarthra longiseta Hupson and Gosss, Rotifera, 1886, vol. 2, p. 6, pl. 13,fig.6. 
Collected by Johansen in a brackish lagoon west of Martin point, Alaska, 
on July 28, 1914; lake south of Bernard harbour, November 28, 1915; on May 
6, 7, and June 12, 1916. 
