SOME ABNORMAL ANNELIDS. 445 
In the trunk many irregularities occur. A remarkable long 
septum runs nearly parallel to the digestive tract anteriorly 
separating 94 from 95 a, and posteriorly 95 a from 95 6. It 
is connected with the walls of the digestive tract by two short 
septa that may he regarded as the continuations of septa 94—95 a 
and 95 a—95 4, though this continuity was not demonstrated. 
An examination of the series of sections shows that this 
longitudinal septum is not continuous, but of slight extent. 
It may be regarded as a veil stretched between 94—95 a and 
95 a—95 b, which seem to be complete transverse septa. Some 
additional complexities affect this region. 
As indicated in this figure, nephridia are found in most of 
the chambers of the body-cavity, right and left. In 93, on the 
right, there is one of the peculiar masses of old setz and 
leucocytes so often found near the posterior end of earth- 
worms. In addition, this part of the body-cavity contained 
a normal nephridium. As far as could be ascertained the 
nephridia are absent in the left of 94 and 96, but they may 
have been destroyed in a dissection previous to sectioning. 
PODARKE OBSCURA. 
This small polychztous Annelid is exceedingly abundant in 
the “eel: pond” at Wood’s Holl, Mass., where it may be seen 
crawling upon the eel-grass or upon the muddy bottom, or 
occasionally swimming free. 
My attention was called to the occurrence of bifid monsters 
in this species by Mr. A. L. Treadwell, of Miami University, 
Oxford, Ohio, who observed as many as fifteen cases of bifur- 
cations of the posterior end, none of the anterior end, amongst 
1500 or more individuals examined in the summers of 1891 
and 1892. Although less than 1 per cent. were abnormal, yet 
a collection of about 100 taken at one time showed five or six 
bifid monsters. 
Regarding these he writes :—‘ The tail sometimes branches 
equally, so that there is no difference between the sides, and 
sometimes the second portion is much smaller than the other. 
