W. C. M‘SINTOSH ON BRITISH ANNELIDA. 381 
the position of the eyes (only the posterior pair, as a rule, being visible in 7. imbricata 
—in which there is a much larger interval also between the anterior and posterior pairs 
than in this form; indeed the anterior pair are near the anterior border, whereas in 
this they are just halfway forward), and the number of the scales (sixteen to twenty 
pairs), which, with the dorsal cirri, have larger and more slender cilia than in H. im- 
bricata. The ventral papilla is smaller than in the latter. The structure of the bristles, 
moreover, is characteristic. In looking over spirit-preparations in which both forms are 
mixed, there is a trimness in the line of the bristles, and a general firmness which is 
peculiar to P. floccosa, and the dorsal and other cirri are shorter, and have no enlarge- 
ment below the tip. 
The dorsal branch of the foot has rather long and more distinctly tapering bristles 
than in H. imbricata, from which, moreover, they are at once distinguished by the 
much closer spinous rows. Bristles of the same length are decidedly more slender 
in this species than in H. imbricata. One of the longer forms is represented in 
Pl. LXVIII. fig. 6, and it may be contrasted with one from a large H. imbricata 
(Pl. LX VIII. fig.7). The tip tapers to a blunt point; and immediately below the bare 
portion very fine and close spinous rows occur. A glance at the latter in running over 
specimens is one of the most satisfactory points in discrimination. The ventral division 
bears superiorly a series (Pl. LX VIII. fig. 8) with long spinous tips (more slender and 
with longer spinous processes than in H. imbricata, Pl. LXVIII. fig. 9) and smooth 
extremities, one or two having no secondary processes. ‘Then a small secondary process 
appears, and the spinous portion gradually diminishes in length, one of the stout examples 
from the middle of the foot being shown in Pl. LXVIII. fig. 10. It will be observed 
that this bifid tip differs quite from that of H. imbricata (Pl. LX VIII. fig. 11), from a 
similar part, and especially in the minute size of the secondary process. ‘The spinous 
rows are also larger and more distinct. Some of the inferior ventral bristles are devoid 
of the secondary process. The Polynoé foliosa of Savigny’ seems to come near this 
species. Savigny only mentions sixteen pairs of scales; but specimens often vary in 
this respect. 
Harmorno#i AREOLATA, Grube. A complete description of this remarkable form is 
not necessary on the present occasion; for Prof. E. Ray Lankester (his Antinoé nobilis) 
and others have indicated the general structure since the original account by Grube (his 
P. areolata). Wt may be mentioned that this species has the same arrangement of its 
eyes as Harmothoé, two being at the posterior border of the head, and two under the 
lobes in front. The dorsal group form a rather conspicuous tuft of elongate slightly 
curved bristles, the curve being about the middle of the latter, so that the bristle is bent 
like a bow in the exposed part (Pl. LX VIII. fig. 12). The spinous rows are dense ; then 
the tip is smooth for some distance, and has a slight though distinct streak, best marked 
1 Syst. des Annél. p. 23. 
3F2 
