PLANKTON OF THE WOODS HOLE REGION 
125 
common among marine animals. Bougainvillia superciliaris, Hybocodon proUfer, 
Nemopsis hacJiei, Tiaropsis diademata, Podocoryne fulgurans, and Tima formosa are 
examples of Hydromedusse having double seasonal distribution. However, hardly 
a single species that occurs normally in the spring has not also been taken in small 
numbers in the fall. With the exception of Podocoryne carnea none of the summer 
visitors have this biannual appearance. 
A regular progression of the more common species of Medusae can usually be 
noticed in the spring. Hyhocodon prolifer appears first, followed closely by Syn- 
coryne mirahilis and Lizzia grata. In early July, as these species reach the end of 
their season, Podocoryne carnea and P. fulgurans appear, followed in August by 
Dipurena strangulata and Bougainvillia carolinensis. The summer and fall species 
always occur in smaller numbers than the spring forms. Certain forms appear to 
be distributed throughout the year. Epenthesis foUeata has been recorded for 
almost every month. 
Fig. 28. — Occurrence of Scyphomedusae and Ctenophora in surface collections from June, 1922, to December, 1923 
Three species of Scyphomedusas are taken frequently in surface collections 
(fig. 28) . The most common {Aurelia jiavidula) appears usually in March, April, 
and May, although ephyr^e have been taken from August to October. 
Table 4. — Occurrence of uncommon Hydromedusx in surface towings 
Species 
Date 
Abundance 
Ectopleura ochracea _. 
Aug. 9, 1904-._ _ _ 
Few. 
Many. 
Few. 
Do. 
Many. 
Do. 
Few. 
Many. 
Few. 
Corymorpha pendula 
Apr. 28 and 29, 1905 
Stomotoca apicata . 
Apr. 27, May 1, and Aug. 15, 1903. 
Staurostoma laciniata 
Apr. 9, 1906 
Eutima mira.. 
Oceania languida. _ 
May 16 and 17, 1904 
Genus Clytia (probably C. bicophora) 
May 10, 1905 
Rhegmatodes tennuis 
Sept. 2 and 14, 1907 
Aglantha conica . . 
Apr. 24, 25, and 30, and May 2, 1906 
Every year in Waquoit Bay immense swarms of strobelias and ephyrse of 
Aurelia appear before the ice leaves. They also occur in varying abundance in all 
local protected coves and shallow bays where eel grass {ZosUra marina) grows in 
abundance. The young apparently rests on the bottom during the ebb tide, rising 
with the flood tide. During this period the water is often filled with them, while a 
few hours later none may be seen. In the spring of 1923 ephyrae were parti<cularly 
nimaerous at Waquoit Bay, although only a single specimen appeared in my collec- 
tions from Great Harbor. By April the medusfe had increased in size, varying 
