PLANKTON OF THE WOODS HOLE REGION 125 
common among marine animals. Bougainvillia superciliaris, Hybocodon prolifer, 
Nemopsis bachei, Tiaropsis diademata, Podocoryne fulgurans, and Tima formosa are 
examples of Hydromedusz 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 Medusz can usually be 
noticed in the spring. Hybocodon prolifer appears first, followed closely by Syn- 
coryne mirabilis 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. Hpenthesis folleata has been recorded for 
almost every month. 
a a 
Baa on Cue a igen ae ns Eee a aa 
Aurelia 
Cyanea, 
Dactylometra 4 
Pleurobrachia 
Mnemiopsis 
Fic. 28.—Occurrence of Seyphomedusz and Ctenophora in surface collections from June, 1922, to December, 1923 
Three species of Scyphomeduse are taken frequently in surface collections 
(fig. 28). The most common (Aurelia flavidula) appears usually in March, April, 
and May, although ephyre have been taken from August to October. 
Taste 4.—Occurrence of uncommon Hydromeduse in surface towings 
Species Date Abundance 
mictopleura ochraceaes-22-- 2-2 ee PAIGE OS 19048 2 ee ee eect Few. 
Corymorpha pendula---_- Aprs2siandi20M1g05 88 oa ee tt Many. 
Stomotoca apicata__-____ Apr. 27, May 1, and Aug. 15, 1903___._-___.__-__.------- Few. 
Staurostoma laciniata-_-- Apr. 9, 1906---______- Do. 
Eutima mira--____-_---- 
Oceania languida_______- 
Genus Clytia (probably May 16, 1905_-_____ ay 
Rhegmatodes tennuis-_- pelaSentnclandel 440076 tos Soe octane anos Many. 
Melani Ghaconica sees ee ihe ee ee a Apr. 24, 25, and 30, and May 2, 1906_____-_-_---_---_---- Few. 
Every year in Waquoit Bay immense swarms of strobelias and ephyre of 
Aurelia appear before the ice leaves. They also occur in varying abundance in all 
local protected coves and shallow bays where eel grass (Zostera 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 ephyre were particularly 
numerous at Waquoit Bay, although only a single specimen appeared in my collec- 
tions from Great Harbor. By April the meduse had increased in size, varying 
