DESCRIPTIONS OF GENERA AND SPECIES 



275 



following table will ahow in a graphic form the resemblances to and differences 

 from other Tubificidae shown by Phreodrilus. 



Phreodrilus subterraneus, BEDDARD. 

 P. subterraneu8, BEDDARD, Trans. Roy. Soc. Ed., 1891, p. 273. 



Definition. Length about 50 mm. ; body semitransparent. Setae one to each dorsal bundle 

 and two in each ventral. Hab. New Zealand. 



\ 



This, the only species of its genus, has a peculiarly delicate appearance which 



differentiates it from any worm with which I have been able to compare it ; the first 

 specimens which I received from Mr. SMITH were obtained from a well ; other examples 

 were afterwards met with in non-subterranean water. I dealt with certain points in 

 the anatomy of the species in a preliminary account (24) which was kter followed by 

 a more detailed description. 



FAMILY NAIDOMORPHA. 



DEFINITION. Aquatic Oligochaeta of small size. Setae usually in four groups upon 

 each segment, sigmoid, bifurcate, hastiform, and capilliform. Sexual reproduc- 

 tion at fixed intervals, between which asexual reproduction by fission occurs. 

 Sexual organs (only known in a few types) are situated far forward, commencing 

 even in the fifth segment. 



This family of Oligochaeta comprises the following recognizable genera : 



(1) Chaetogaster, BAEK. (5) Pristina, EHRENBERG. 



(2) Amphichaeta, TAUBER. (6) Uncinais, CZERNIAVSKY. 



(3) Tfais, 0. F. MtJLLER. (7) Chaetobranchus, BOURNE. 



(4) Bohemilla, VEJDOVSKY. (8) Dero, OKEX. 



N n 2 



