W. C. M'lNTOSH ON BEITISH ANNELIDA. 381 



the position of the eyes (only the posterior pair, as a rule, being visible in //. wibricata 

 — 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 //. im- 

 brkata. 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. Jloccosa, 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. imhricata, 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 

 PI. LXYIII. fig. 6, and it may be contrasted with one from a large H. imhricata 

 (PI. LXVIII. 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 (PI. LXVIII. fig. 8) with long spinous tips (more slender and 

 with longer spinous processes than in H. imbricata, PI. 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 PI. LXVIII. fig. 10. It will be observed 

 that this bifid tip differs quite from that oi H. imbricata (PI. LXVIII. 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 Polynoe foliosa of Savigny' seems to come near this 

 species. Savigny only mentions sixteen pairs of scales; but specimens often vary in 

 this respect. 



Haemothoe aeeolata, Grube. A complete description of this remarkable form is 

 not necessary on the present occasion ; for Prof. E. Ray Lankester (his Antinoe nobilis) 

 and others have indicated the general structure since the original account by Grube (his 

 P. areolata). It may be mentioned that this species has the same arrangement of its 

 eyes as Ilarmothoe, 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 (PI. LXVIII. fig. 12). The spinous rows are dense ; then 

 the tip is smooth for some distance, and has a slight though distinct streak, best marked 



' Syst. dee Annel. p. 23. 



3f2 



