248 L. N. G, EAMSAY. 



St. Joseph (6, p. 247) notes that from the 13th to the 4th last segment, 

 the spinigers of the notopodial bundle are replaced by others, similar, but 

 with a much longer terminal appendage. This appears to be the case, 

 too, in some at least of the Plymouth specimens, although the change 

 seems to occur posterior to the 13th segment. I have not paid much 

 attention to this point. He also states that homogomph as well as 

 heterogomph spinigers occur in the lower neuropodial bundle. This I 

 have not found to be the case. 



Among the material collected by Mr. Orton on 25th February is a 

 male heteronereis, apparently in the fully developed condition, and two 

 other males at earlier stages of development. 



St. Joseph (6) has described both the male and female heteronereid 

 forms in detail. Claparede did not meet with either. 



The above-mentioned male agrees very well with St. Joseph's descrip- 

 tion. It is 12-5 mm. long, with 58 pairs of parapodia. The noto-cirri of 

 the first seven pairs of parapodia are much swollen (Fig. 7). The change 

 to the swimming-parapod occurs between the 14th and 15th pairs (St. 

 Joseph found it to occur between the 15th and 16th pairs — the variation 

 is unimportant). In the 43rd to 45th pairs a transition towards the form 

 of the third region occurs, the cirri and lobes becoming shorter and smaller, 

 and the paddle-setse decreasing in number. 



The third region may be reckoned as commencing at the 44th pair, 

 where the peculiar, large, simple setae, figured by St. Joseph, commence. 

 These are from one to three in number, and continue till the last setigerous 

 segment. They are, I believe, to be regarded simply as derived from 

 normal heterogomph falcigers by the fusion of the appendage with its 

 socket. Ground for this belief is afforded by the analogy of the large 

 bristles which occur in the posterior regions of Nereis pelagica and 

 N. agassizi. In these the appendages are in some cases completely free, 

 in others totally fused with the shaft. 



Several females of the nereis-form, obtained on 20th March, were filled 

 with ova. These are of very large relative size (0'24 mm. diameter). 



The synonymy at the head of this section requires some ex- 

 planation. 



St. Joseph in his detailed and excellent account of Leptonereis vaillanti 

 never refers to the possibility of this species being identical with Clapa- 

 rede's. He does not indicate any points of difference between the two 

 species, and indeed, the only mention he makes of L. glauca is to 

 say that the setse of vaillanti are exactly similar to those figured by 

 Claparede for the Mediterranean form. 



