808 



ON THE CH^TOSOMATIDyE, 



Xotochti'tomma tenax, gen. et sp.nov 



Total length 



Length fi'om anterior end to neck -curve 

 Length of trunk covered bj' rows of setne 

 Lengtli from tip of tail to anterior end of 



of seta-... 

 Length from tip of tail to anus ... 

 Length of tail 



Greatest width at anterior end ... 

 Width at neck-curve 

 Greatest width of trunk ... 

 Width at level of ventral setK ... 

 Width at beginning of smooth tail-part 

 Length of rostrum 

 Length of setx" on rostrum 

 Length of hairs on head ... 

 Length of hairs on trunk ... 

 Length of ventral setre, outer rows 

 Length of ventral setae, inner rows 

 Number of setoe in ventral rows, outer... 



Number of setce in ventral rows, inner... 



Length of penial setct 



Length from anterior end to genital pore 



0-432 



NoTOCH^TOSOMA CRYPTOCEPHALUM, gen. et sp.nov. (Plate 1.). 



In the same material from Yaiicluse, Port Jackson, in wliich 

 specimens of JS^. tenax were obtained, I found a single male 

 individual of another species, which very closely resembles it in 

 general form. There is a total absence of a head-demarcation, 

 and, in shape, the worm looks very like a Nematode (Plate 1.). It 

 is elongated and cylindrical, 1*056 mm. long, and tapers gradu- 

 ally towards each end. The anterior end is rounded; the posterior 

 end terminates in a sharply pointed tail. 



Four rows of ventral, locomotor sette (Text-fig. 5 7) are present, 

 beginning 0*048 mm. in front of the anus. The body is broken 

 in the region of the seti\3, st) that the number of the setse and 

 the length of the body covered by them, cannot be determined 

 with accuracy; but there are about seven compound seta3 in each 



