PLANKTON OF THE WOODS HOLE REGION 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 (Miller). See Figures 23 and 24. 
Dictyocha fibula, Ehrenberg. 
Distephanus speculum, Heckel. 
Glenodinium compressa, Calkins. March 4, 1923. 
Gonyaulax tricantha, Jérgensen. 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 davidofi, Daday. October 14, 1922. 
Tintinnopsis sp. See Figures 23 and 24. 
BS; g 
Ble Cee yecrray orcs emer im ae a” | 
Bongainvillia superoiliaris 
Gemmaria oladophora 
Obelia spe 
Podoooryne fulgurans Hi 
Podocoryne carnea rH 
Stomotooa apiceata ce 
Hotopleura ovhracea 
Hybooodon prolifer H ; 
Lizsia grata 
Syncoryne mirabilis 
Syncoryne producta 
Turritopsis mutricula 
ilercertium campanula 
Tiaropsis diademata 
Dysmorphosa fulgurans 
Bougainvillia carolinensis 
Dipurena strangulatsa 
Fic. 25.—Occurrence of Hydromedusz in surface collections from June, 1922, to December, 1923 
CGLENTERATA 
One hundred and sixty species of ccelenterates 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 
Seyphomeduse and ctenophores are also recorded on individual charts. 
The diagrams show clearly that there are definite seasons of occurrence for 
the various species of ccelenterates. In most cases the species have a long spring 
maximum and also a short one in the fall. Such a semiannual appearance is not 
