112 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 128 



Table 7. — Gross analysis of plankton. Point Barrow, Alaska, August-September 

 1948, September 1949-July 1950 — continued 



3-14-50 I tunicate larva 

 3-29-50 Foraminifers ; few 



4- 8-50 Tintinnids, few ; nematodes, few ; tunicate larva, i ; eggs, unidenti- 



fied, C 

 4-15-50 Tintinnids, R; tunicate larvae, 3; fish eggs, few (somites visible) 

 4-24-50 Tintinnids, few; tunicate larvae, 2 



5- 2-50 Tintinnids, few; tunicate larvae, none; dinoflagellates, 3; eggs, C 



5- 9-50 2 eggs ; tunicate larvae, none 

 S-17-50 Eggs, few; tunicate larvae, i 



5-23-50 I yg. Arctic cod ( ?) ; tunicate larvae, none 



5-30-50 I nematode (microscopic branching algae have been present for 4 

 weeks) 



6- 6-50 I huge trochophore (possibly of the echiuroid Hamingia arctica) 

 6- 9-50 I huge trochophore 



6-16-50 2 huge trochophores 



6-20-50 I huge trochophore 



6-20-50 Eggs of 2 sizes ; fish eggs 



6-23-50 Eggs of 2 sizes, C 



6-23-50 Few huge trochophores 



6-27-50 Few huge trochophores 



6-27-50 Eggs, Ig., C ; eggs, sm., A ; eggs, very sm., few 



6-30-50 Eggs, Ig., few; eggs, sm., A 



7-13-50 I yg. Arctic cod ; sm. chaetognaths, C 



Examination of the above lists of plankton sampling reveals several 

 items of interest. The spiny types of diatoms were absent from No- 

 vember I, 1949, to March 23, 1950, but several circular forms were 

 present throughout the winter. The chain type of diatoms became 

 abundant in the spring before the spiny type. 



The fact that the winter tows were made vertically and hence cov- 

 ered a very small area as compared with tows made in the usual 

 manner, reduces to little significance the absence of any one form from 

 the plankton for one or two hauls. But the continued absence of a 

 form must have significance even though the hauls were not extensive. 



That not a single echinoderm larva appeared in any of the hauls 

 from November i, 1949, until July 13, 1950, when it was no longer 

 possible to take hauls, is surely an indication that no echinoderms 

 were spawning during the winter. 



The trachyline medusa Aglantha digitate was present throughout 

 the winter, and the gonads began development on March 29, 1950. 

 Although not shown on the above lists, adults of the jellyfishes Cyanea 

 and Chrysaora were present throughout the winter (see "Trapping 

 Through the Ice"), and eggs and swimming larvae were observed in 

 Chrysaora on November 19, 1949. This fact, plus the presence of an 

 ephyra on July 13, 1950, indicates that much goes on under the ice 

 in winter. The presence of the medusa Rathkea octopunctata on July 



