PLANKTON OF THE WOODS HOLE REGION 163 
tively coarse and both ends were broken. Lohmann gives 17 mm. as the average 
length of the “‘Haus” of Ovkopleura albans Loeck. It is difficult to understand 
how copepods could be induced to enter such a small opening. Possibly, as in 
O. albans, the complete “‘Haus” is made up of two compartments—one of coarse 
and the other of fine mesh. The currents of water produced by the movement of 
the animal’s tail cause microorganisms to collect in the fine mesh. This tich food 
center may attract 
. 
the copepods, which § r 5 Fi 3 a & 3 é 3 é 
crowd into the outer ol anes < 5 5&5 2 8 6 B& @B 
opening. The re- i993 | 
moval of the soft 
partsof thecopepods 1894 
was no doubt the 
work of protozoa. I 
have observed them 
completely clean out 
a decapod megalops jg97 
in two days. The 
difficult thing to im- 1898 
agine, however, is 
how so many cope- 1899 
pods could get into 
such a small amount 1900 fie 
of space. Lohmann 
found that a new 
“Haus” is secreted 
every six hours. 
This fact accounts 1993 
for the great number 
taken. 1904 
Only one species 
(Oikopleura _longi- 1905 
cauda (Vogt), listed 
by Pratt as Appendi- 1906 
pestis ee al noe [ela a 
Fe NG OPN el 
) 
corded from the Fia. 64.—Occurrence of Appendicularia during successive years. No record was made 
region. Neither after 1904 
member of the genus taken this year contains the ‘‘Kapuze” characteristic of 
Pratt’s species. The winter form agrees very closely with, and probably is, O. van- 
hoffent Lohmann, while the summer form has many of the characteristics of O. dioica 
Fol. At the time lack of sufficient literature prevented a final determination, and 
the preserved forms are not in a sufficiently good state of preservation to be iden- 
tified positively. 
