342 ALFRED GIBBS BOURNE. 



System of the Naidomorpha. 



The Naidomorpha are Oligochseta in which the central 

 nervous system presents cerebral ganglia^ pharyngeal com- 

 missures, and a ventral cord. The cerebral ganglia are always 

 separated from the epiblast. 



In addition to sexual, asexual reproduction by means of 

 gemmation and subsequent fission occurs. A clitellum de- 

 velops in sexual individuals at the breeding season. 



The setse are placed in four rows. They are capillary, spear- 

 shaped, or crotchet-shaped.^ 



There are, as a rule, more than two setse in each bundle. 



A stomachal enlargement of the alimentary canal occurs in 

 segment vii or viti. They are all aquatic, living in fresh or 

 sea water. Branchial processes may be present or absent. 



To this definition must be added, when information is 

 available, the position of the various generative organs. The 

 position of the testes and ovaries given by Vejdovsky does not 

 agree with my observations on N. barbata and P. littoralis. 



According to Vejdovsky, the following genera form the 

 family of Naidomorpha : — 



Aulophorus, Schmarda. 

 Dero, Oken. 



Nais, s. str., O. F. Muller. 

 Bohemilla, Vejdovsky. 

 Ophidonais, Gervais. 



1 I do not use these three terms to correspond exactly to Haar-borsten, 

 Spalt-borsten, and Haken-borsten. The capillary setaj are the long hair-like 

 setce, which maybe serrated as in Bohemilla; the crotchet-shaped setse 

 have the well-known /-shape, with the forked free extremity ; while what I 

 have called spear-shaped setsc are such setse as present characters to some 

 extent intermediate between those of the foregoing types. They may be 

 straight with a sharp-pointed end, or straight and bifurcated at the end, or 

 somewhat crook-shaped. 



