64 W. H. TALIAFERRO 
The planarian referred to above belongs to the genus Planaria, 
but as to the species there is some question, owing to the fact 
that the reproductive organs were not observed and that in 
these organs are found the chief characteristics which at present 
determine the species. Specimens have been collected from the 
same locality, at irregular intervals, by Professor Kepner for 
nine years and by the author for five years. In spite of these 
repeated attempts, no sexually mature animals have been ob- 
tained. Moreover, specimens have been reared in the laboratory 
and kept under almost constant observation for nearly two years. 
During this period the animals reproduced solely by asexual 
fission. 
In an earlier report of this work (717) the planarian under 
consideration was considered a new species. At the present 
time, however, the writer is of the opinion that it is so closely 
related to Planaria maculata Leidy, that it may be considered 
a variety of this species. In shape, size, general color, and nor- 
mal fission, it agrees very well with the description given by 
Woodward (’97) Curtis (’02), and Bardeen (01) for Planaria 
maculata. In color it is, however, very much more variable 
than maculata, judging from the descriptions, of this species, ex- 
tending from an almost gray through brown to almost black. 
There are also other respects in regard to which the specimens 
under consideration do not agree with the descriptions of Planaria 
maculata. Most prominent among these is the structure of the 
enteron. The descriptions indicate that the enteron of Planaria 
maculata has many anastomosing diverticula. In the planarian 
used in these experiments there are relatively few, certainly far 
fewer than are shown in the figures of Curtis (02). There is also 
a marked difference in the reactions. The planarians used in 
this work oriented to light very much more precisely than did 
specimens which agree more closely with the description of 
Planaria maculata obtained from other localities. 
In operating, three methods for quieting the worms were found 
useful; viz., lowering the temperature with a salt-and-ice mixture, 
adding a few crystals of chlorotone to the water, and treating 
the animals with carbon dioxide. Of these three methods, the 
