22 W. BLAXLAND BENHAM. 
like that of Sabella.” It agrees more closely with this species 
than with any more recently described, such as C. albida, 
Biirger, so that I must leave the matter of species open. 
The hardened specimen was sectionised as follows :—(1) The 
anterior end was’cut sagittally (vertical longitudinal); (2) the 
hinder end was cut horizontally, though rather obliquely 
to the horizontal plane; (3) the middle region of this body 
was transversely sectionised. The stain used was carmalum, 
though some sections were stained with picro-carmine. 
With regard to the posterior “segmented” region of the 
body, one is struck at once by the fact that at the level of each 
of the four constrictions there is a transversely arranged 
row of small nuclei traversing the longitudinal muscles. They 
are readily seen even with a low power (fig. 3), and are more 
evident at the deeper constrictions a, B, than at the shallower 
ones ¢, D. 
What appears to be the commencement of the phenomenon 
is illustrated by the sections across the constriction c (fig. 4). 
At this point the tissues are as yet perfect—there is no 
rupture. The section figured passes through the lateral line 
of the body, on one side cutting along the nerve (NV); at the 
opposite side the nerve is notinvolved. The nuclei constituting 
the transverse row are not as yet as definitely arranged as they 
will be; nevertheless they are more numerous along the level 
of the constrictions than elsewhere, and take a deeper tint in 
the stain. It may here be mentioned that the accompanying 
figures are drawn with the camera, and so far as was possible 
every nucleus is put in its true position, except in the case of the 
epidermis and intestinal epithelium where these are involved. 
The nuclei which are thus conspicuous appear to belong to 
the connective tissue in which the longitudinal muscles are 
wrapped ; they are smaller and more deeply stained than those 
of the muscles. Although the impression given by the section 
fig. 4, through the region c, appears to indicate an irregular 
transverse line, yet at a further stage this line becomes very 
much more distinctly transverse, and, moreover, it is in reality 
double; the nuclei are arranged into two rows close to one 
