LOLIGO PEALII. 115 



3. Another ganglionic mass, the abdominal ganglion, possi- 

 bly formed by the fusion of two ganglia, lies just below the exter- 

 nal opening of the kidney, where it can be seen as a brown mass, 

 through the body-wall. It lies on the elongated commissure 

 that connects the two visceral ganglia. The commissure may be 

 followed by dissection. 



The cerebral ganglia are the most centralized. Besides being 

 connected with each other by a commissure dorsal to the esopha- 

 gus, and being intimately connected with the pleural ganglia, 

 each cerebral ganglion is connected with the corresponding buc- 

 cal and pedal ganglion, and, through the pleural, with the visceral 

 ganglion. The visceral ganglia are connected with each other 

 by a long commissure on which the abdominal ganglion is placed. 

 Each pedal ganglion receives connectives from the cerebral and 

 from the pleural ganglion of the corresponding side. 



Draw figures of the nervous system and compare them with 

 the clay model. 1 



LOLIGO PEALII. (The Squid.) 



Specimens of this or closely related species are rather common 

 along the Atlantic coast of the United States. They are active 

 swimmers, but may occasionally be seen in shallow, quiet water 

 near the shore. The movements and positions of adult speci- 

 mens in aquaria should be studied. Do you know what they 

 eat and how they capture their food ? 



Study a small living specimen in a jar of sea-water and no- 

 tice: 



1. Its general shape and distinct head. 



2. Its position in the water. For convenience, the lower 

 surface may be referred to as ventral, but this is not to be con- 

 sidered as morphologically the same as the ventral surface of 

 other Mollusca. What parts are kept moving? Why is water 

 pumped when the animal is not swimming? 



1 Instructors will find that a model prepared by sticking lumps and 

 strands of modeling clay on a cylindrical graduate, to illustrate the positions 

 of the ganglia and connectives on the esophagus, will greatly aid the 

 students. 



