Gatlu Marine Laboratory, St. Andrews. 29 



rescniljliiifi; sjiatula from tlic breadth of tlic wings, grada- 

 tions occniriiig between the tlie two — showing a long hair- 

 like eontiniiation of the shaft as well as the broad wings. 

 The dorsal forms have a long shaft slightly curved backward 

 toward the tip, which is finely tapered and furnished with 

 wings of moderate breadth, which insensibly disappear below 

 the hair-like tip. The inferior bristles of the same group — 

 that is, those next the inferior hook-rows — have wings so 

 sliort and broad as to make the tip sj)atulate and often 

 ■with a slender hair- like continuation in the middle, lioth 

 types of bristles are frequent in the Sabellids. Similar 

 bristles occur in the anterior "aljdomiual^^ region, but the 

 last six at least are very long, attenuate, and project 

 prominently outward, whilst scarcely a trace of a wing is 

 Aisiijle, even in the nl0^t anterior long tuft. 



A series of minute bristles with the si)atu]ate tip bent at 

 an angle accompany the anterior hooks, which commence 

 on the second bristled segment. These occasionally project 

 lieyond the line of the great fangs of the hooks in situ. 

 'J'he hooks, of which there are about eleven in each row, 

 tlicmselves have a remarkably long main fang with three or 

 four spines in lateral view above it, making a high crown, 

 the posterior outline is much curved and runs to the basal 

 process, whilst the gulf between the gi'eat fang and the prow 

 IS rather narrow. The posterior process is comparatively 

 long. In the posterior hooks the spikes above the great 

 fang are more numerous, as well as more evident. The great 

 fang itself is powerful and slightly curved. The gulf 

 anteriorly is as mcII marked as in the thoracic hooks, but 

 the prow is proportionately broader and more blunt, and the 

 posterior process considerably smaller and shorter. The 

 number of the hooks anteriorly is similar to that found 

 in the "thoracic" region, but posteriorly they diminish, so 

 that in the antepenultinmte there may be only one. 



The change in the setigerous and uncinigerous processes 

 occurs at the tenth segment, the posterior region having the 

 hooks dorsal and the bristles ventral. 



The eleventh species, Dasychone argust, Sars, a form not 

 to be distinguished from b'ubc//a lucallaua, D. Chiaje, is 

 generallydistnbuted throughout Britain. When the branchiae 

 have been shed by the annelid, the cephalic plate has the 

 edge of the collar projecting beyond its surface, which shows 

 at the dorsal inflection two small processes or folds, from 

 which a pear-shaped area passes ventrally to end in the oral 

 ridge. The entire surface is thus symmetrically mapped 



