638 MR J. T. CUNNINGHAM AND MR G. A. RAMAGE ON THE 



transverse line, concave forwards. First somite bears neuropodial and noto- 

 podial setae, but no branchiae. Branchiae bent over the back in all the following 

 somites ; lamina extending along the outer edge of the branchia, little more 

 than half-way in anterior somites, a less distance posteriorly. Length, 7-12 cm. 

 Colour in life distinctly green ; branchiae red, from the blood within them. 

 Segments longer than in N. coniocephala. 



This species has not before been recorded as occurring on the British coasts. 

 After careful comparison, we are obliged to conclude that our specimens are 

 not specifically distinct from Clarapede's N. cirratulus, though there are minute 

 points of difference. It is not probable that these are to be attributed to 

 inaccuracy on the part of Clarapede : it is more likely that the specimens from 

 localities so far apart as the Firth of Forth and the Bay of Naples present 

 differences which are too slight to separate the species into two. In Clarapede's 

 figure of the parapodium and branchia, the lamina of the latter extends nearly 

 to the lip, and has at its own extremity a rounded outline. In the anterior 

 somites of our specimens the lamina does not extend so far along the branchia, 

 and has distally a pointed corner (fig. 2 a). In the posterior somites of our 

 form the lamina is of still smaller extent, and is rounded as in Clarapede's figure. 

 That author describes the ova very accurately ; their structure is peculiar in 

 two respects. They have a well-developed vitelline membrane, which is covered 

 externally with a reticulation of hexagonal meshes. The shape is that of a 

 slightly flattened ellipsoid, and round the longest circumference is a single series 

 of vacuoles in the external region of the vitellus. The meaning of these vacuoles 

 is unknown. Claparede observed that when, after the ova had escaped into 

 the water, the vitellus contracted, the vacuoles were ejected from it as vesicles 

 into the perivitelline space. We have seen the formation of the perivitelline 

 space, but did not observe the ejection of the vesicles, but this phenomenon 

 was observed by one of us in the ovum of N. coniocephala (figs. Id, 1 e), 

 where the vesicles form a double series. 



The early development of this species is very peculiar in certain points. 

 The ova are plagic, and we recognised them early in February amongst the pro- 

 duct of the tow-net worked close to the shore. In the vessels of the Laboratory 

 the ova sank to the bottom, which shows that they are heavier than the water, 

 and only kept in suspension by the agitation due to the tides and waves. The 

 segmentation we have not studied in detail : but from the appearance of the 

 single stage observed it seems that the segmentation is complete and unequal, 

 and that a gastrula is produced by epibole, as in other Chaetopoda. At a later 

 stage two rings of long S-shaped cilia appear, one at the broader anterior end 

 of the body, the other at the posterior end. The vitelline membrane persists at 

 this stage, and for long afterwards forming a cuticle for the larva, and retaining 



