7G 



i. The Nervous Syctem. 



The nervous system oL' "Ship-worms" I have studied in 

 the larval and subsequent stages of Xylotry^i fimbriata, 

 and in the adult of T. naval is and T. norvegica. V/hile my 

 description ai plies especially to o: lirst oi i.-se, the 

 others are in such close agreement, that we seem justified 

 in believing that there is great uniformity in this regard 

 in all of the species of the Teredinidae , and that the de- 

 scriptions heretofore given have been erroneous. 



The Nervous System of the Larva. - In the larva the prin- 

 cipal elenients of the adult are present. However, in 

 their relations to each other, their embryonic development 

 is not corqrlete; and in their relation to other structures 

 great changes take place along with the change in the gen- 

 ei*al organisation. The general plan i;^ r^hown in figs. 2 

 and 59, the latter representing a dorsal view of the ner- 

 vous system of a larva just attaclied. In front ^^ ...vi on 

 the sides of the mouth are the two cerebral ganglia, (c) 

 separated l" " •'■■••■ -hort co: ii lissure , and each sending a 



