264 JOURNAL OF COMPARATIVE NEUROLOGY. 
in the summer from 12°C. to 14°C. The temperature recorded 
in the case of Aulastomum is that of the room. 
Cerebratulus sp. 
Several species of Nemertians are found in abundance at 
Pacific Grove, but most of them are of too delicate a structure 
to be experimented with by the method employed by us. 
a N 
a nn A eee eee 
POTTY TRICE et IT ILC UML DUA WALA T LAC ASA SSA asm 
WAVY 
Fig. 1. Cerebratulus sp. Postero-anterior. Length of nerve cord between dis- 
tal and proximal electrodes: 5 cm. Rate: 8cm. persec. Time: 50d. 
Vv. per sec. 
We succeeded in securing but two specimens of Cerebratu- 
lus of sufficient strength. These specimens were about 30 cm. 
in length, but showed the same tendency to break into small 
fragments on irritation, that was manifested by their smaller 
relatives. Decapitation failed to quiet them. However, we 
secured an unbroken portion of a few centimeters in length from 
the anterior part of each specimen. The Nemertians possess 
one dorsal and two lateral longitudinal nerve cords, in which 
they resemble the Platodes rather than the Annelids. No at- 
tempt was made to isolate the nerve cords. The stimulus 
reached the cord by application of the electrodes to the ventral 
side of the body. Single induction shocks were not always 
sufficient for excitation from the distal point of stimulation. 
The required intensity of the stimulus is much greater in this 
species than in any of the Annelids included in this work. 
The length of the portion of the nerve cord between the 
two points of stimulation was determined in the specimen while 
crawling in the aquarium. 
