PLANKTON OF THE WOODS HOLE EEGION 
123 
in surface collections in calm weather. Some six species were distinguished, but 
positive identification was impossible because there was not sufficient literature 
available at the time. 
The following protozoa were identified from the surface collections of 1922-23: 
Acineta tuberosa, Ehrenberg. March 4, 1923. 
Ceratium fusus (Ehrenberg). See Figures 23 and 24. 
C. longipes (Bailey). February to June, 1923. 
C. macroceros (Ehrenberg) . See Figures 23 and 24. 
C. tripos (Muller). ^ See Figures 23 and 24. 
Dictyocha fibula, Ehrenberg. 
Distephanus speculum, Haeckel. 
Glenodinium compressa. Calkins. March 4, 1923. 
Gonyaulax tricantha, Jorgensen. April 21, 1923. 
Gymnodinium gracile, Bergh. 
Heterophrys sol, Ehrenberg. 
Peridinium depressum. Bailey. See Figures 23 and 24. 
P. oceanicum var. oblongum, Aurivillius. Figures 23 and 24. 
Tintinnopsis davidoffi, Daday. October 14, 1922. 
Tintinnopsis sp. See Figures 23 and 24. 
BoogaloTlIlla sopcralllarls 
Oamarla olMophora 
Podoooryne fulgorans 
Podocoryne oamea 
Stonotooa aploata 
iSotopleTira obhraoea 
Bybooodon prollfer 
Iliila grata 
STBOOryne nlrabllle 
Synooryne products 
Torrltopsis nutricrala 
JUleroertltca oanpaxmla 
Tlaropsls dladeoata 
Uysmorphosa fulgurane 
Boa^nvlllla oarollnensls 
Otpprena Etrangolata 
Fig. 25.— Occurrence of Hydromedus® in surface collections from June, 1922, to December, 1923 
CCELENTERATA 
One hundred and sixty species of coelenterates were recorded from the Woods 
Hole region by Sumner. Of these, 132 were Hydrozoa, 5 were Scyphoza, and 8 were 
Ctenophora. Thirty-eight species are listed in the tow records of Vinal N. Edwards 
for the years 1893-1907. Figures 25, 26, and 27 show the maximum occurrence 
of the more common species, while in Table 4 the rarer forms, together with the 
particular dates of appearance, are noted. The records of the more common 
Scyphomedusas and ctenophores are also recorded on individual charts. 
The diagrams show clearly that there are definite seasons of occurrence for 
the various species of coelenterates. In most cases the species have a long spring 
maximum and also a short one in the fall. Such a semiannual appearance is not 
