174 ANNELIDA POLYCHAETA. 



teeth. On the ventral side (VII and VIII) a belt of' two rows 

 of teeth is to be found. 



From the foregoing description , based on the examina- 

 tion of a great number of specimens, it may be concluded, 

 that the arrangement of the paragnathi is very constant; 

 the number of small teeth in the lateral groups varies 

 within certain limits, but on the dorsal side the median 

 maxillary group only appears to be liable to some varia- 

 tion , as is already stated by other authors. 



Among the species of the Perinereis-d'ivision , characte- 

 rized by having in group V. a triangular patch of three 

 teeth , only a small number are described , which have in 

 group I. more than 2 paragnathi ; they are : IV. perspicil- 

 lata Gr. *), N. Anderssoni Kgb. 2 ) and N. exsul Kgb. 2 ). N. 

 pei'spicillata , only known in atocous state, is distinguished 

 from our species by the longitudinal series of paragnathi 

 in group I , by the shortness of its palpi and by having 

 the dorsal cirrus not longer than the superior ligule. Our 

 knowledge of the characters of the two other species is 

 too scanty. 



Nereis ferox Hans. (PI. 7, figs. 6 — 8). — Recherches 

 sur les Annélides, recueillies par M. Ie Prof. E. van Be- 

 neden pendant son voyage au Brésil et a la Plata, loc. cit. 

 p. 14, pi. IV, figs. 34—39. 



Length of a specimen, with regenerated posterior region, 

 37 mm.; anterior region of the body considerably enlarged. 

 Cephalic lobe longer than broad ; its anterior part in front 

 of the eyes narrower. The head measures a little more in 

 length than the antero-posterior diameter of the two suc- 

 ceeding segments (the proboscis being extruded). Antennae 

 two thirds of the length of the cephalic lobe ; palpi large , 

 about of the same length as the antennae. The antero- 

 posterior diameter of the buccal segment once and a 



1) Annulata Semperiana, p. 90, T. IV, fig. 10. 



2) Annulata nova, p. 175. 



Notes from the Leyden Museum , Vol. XI. 



