LEPTONEREIS GLAUCA CLPDE. AND GENUS LEPTONEREIS KINBERG. 249 



Comparison of the descriptions and figures published by these two 

 authors leaves us with the following points of difference : — 



(a) The Dinard specimens differ slightly in colour. 

 (6) Their noto-cirri are shorter. 



The general form of the head and its appendages, the proboscis and 

 jaws, the peristomial cirri, the parapodia (except for the noto-cirri), the 

 setae, the dimensions of the whole animal and number of segments — all 

 are identical in the two. 



As to the points of difference, {a) hardly amounts to more than the 

 fact that the Mediterranean specimens were more strongly pigmented 

 than those from Dinard. The Plymouth ones, it appears, are still 

 less so. 



Then coming to (6) one may note that the noto-cirri of the Plymouth 

 specimens are almost intermediate between those of St. Joseph's and 

 those of Claparede's. It does not seem that much importance should be 

 attached to this point. 



Secondly, I have come to the conclusion that Langerhans' Leonnates 

 pusillus from Madeira is at least very closely related to Claparede's 

 Leptonereis glauca. Langerhans' description and figures leave no doubt 

 that the two species are of the same genus (in view of the presence of 

 papillae on the proboscis to Lejjtonereis) . In Leonnates fusillus a papilla 

 is present in area II on each side, in addition to those on the basal ring 

 (these are only visible " bei sehr genauem Zusehen "). Also the peri- 

 stomial segment apparently was distinctly longer than in Lepto7iereis 

 glaum. Many examples showed a large yellow spot on the cephalic lobe ; 

 this, however, was not always present. 



In other respects Leonnates pusillus is identical with LejJtonereis glauca. 

 Langerhans kept some specimens in captivity for some time and wit- 

 nessed the change to the heteronereid form, in both male and female. 

 His observations on these agree essentially with St. Joseph's. The 

 large, brown setae appeared in the same way in the posterior eleven pairs 

 of parapodia of the male. 



Langerhans concludes his description of this species with the sugges- 

 tion that an examination of fresh material will show that in species such 

 as Leponereis glauca and L. cebuensis the proboscis is furnished with 

 papillae similar to those of Leonnates pusillus. After a lapse of thirty- 

 five years his prediction has been fulfilled. 



