94 



THE NERVOUS SYSTEM OF ARTHROPODS. 



likely to be associated with greater brain development and 

 with higher or more complex brain functions. 



Among the lower Myriapods, such as lulus and Geophi- 

 lus, in wdiich the limbs, though very numerous, are feeble 

 and ill-developed, the nervous system exhibits only a 

 slight advance over the forms which it presents among 

 the higher Annelida. In lulus (fig. 33) the single 

 abdominal cord shows almost no traces of ganglionic 

 swellings, owing to the great number of the small nerves 

 given off on each side, along its entire length, which are 

 distributed to the hundreds of small segments entering 

 into the composition of the body. 



Pio 33.— Anterior part of the Nervous System of lulus (Owen), a, a. Cerebral 

 ganglia ; c, c, optic nerves ; d, d, antcnnal nerves ; b, nerves of the paljiless 

 mandibles ; g, oesophageal cords ; e, f, stomato-gastric nerves ; h, motor nerves to 

 the maxillse, proceeding from the part wliich corresponds with the sub-oesophageal 

 ganglia, here fused with i, i, the ventral cord. 



The brain (a, a), elongated transversely, is divided by a 

 slight median furrow, and is continuous with the short 

 and thick optic nerves (c, c). Two separate nerves 

 are received from the antenna) on each side [d, d), below 



