Pt Se! فم‎ 
480 DR. BAIRD ON A NEW SPECIES OF BRITISH ANNELIDES. 
ever, who has examined Ch. pergamentaceus, takes no notice of them. In our British 
species they are so observable that they strike the eye at the first sight as most remark- 
able. A similar bundle or fascicle of spines, however, is mentioned by Stimpson as 
having been observed by him in the third pair of feet of his Ch. Capensis, He describes 
them as “a fasciculus of stout, black, truncated sete at their bases." The tenth seg- 
ment has the feet strongly developed, as in Ch. pergamentaceus, the dorsal branch 
extending outwards to the length of nearly an inch (figs. 1 & 2,e). It is of a lanceolate 
shape, and encloses within its substance a fascicle of numerous long setze, of a yellowish 
colour, simple, straight, and blunt-pointed (fig.5). These are not exserted, but appear 
merely to support and give firmness to the pinnule. The ventral branch (fig. 1^) is in 
the form of a broad, fleshy, flat plate, bilobed, attached to and lying across the ventral 
surface of the animal, and having its free edges armed all round with a row of short 
simple setze, of the same form as those of the dorsal branch. (wf 
The second or middle portion of the body of the animal (figs. 1 & 2, g) is much narrower 
than the first or anterior, and much longer. It is cylindrical in form, and has a deep 
eroove or furrow running along its ventral surface, and consists of four segments, The 
appendages attached to these segments are considered as fect by Milne-Edwards, but 
they differ very much from those of the anterior part in form and structure, They con- 
sist of two branches, the ventral one being exactly similar to that of the tenth pair of 
anterior feet. It is in the form of a broad, flat, fleshy lobe, bilobed like that of the tenth 
pair, and having a row of short straight setze on the edges. The dorsal branch has the 
form of a large membranous sac or vesicle which lies across the back, and is believed 
by Milne-Edwards (in Ch. pergamentaceus) to act the part of a branchial organ. All 
the four pairs of feet are similar in form; but these sacs appear to bear little or no 
relation to branchizm, as most of them are filled with solid matter arranged in the 
form of cylinders, from three to six or eight to each sac (fig. 6). This matter seems to 
me to be fecal, and is composed (as seen when broken down and placed under the 
microscope) of a rather dark amorphous substance, interspersed with numerous globular 
transparent bodies, which are evidently Diatoms, and still greater numbers of what 
appear at first sight to be small Foraminifera, but are most probably crystallized bodies, 
as they do not show any distinct structure. The transparent globular bodies I at first 
considered might be ova; but mixed up with them are smaller bodies of a globose shape; 
which are evidently Diatoms. The sacs themselves communicate with the intestine, and 
I therefore presume them to be chiefly cecal, and not branchial*. 
The third or inferior division of the body (figs. 1 & 2, ^) consists of twenty-seven seg- 
ments in the most perfect specimen I have seen; but they seem to vary very much, as n9 
— specimens agree, one having twenty while another has only thirteen, and yet the 
animals appear to be mature in growth. "The body is very brittle about the middle por- 
tion, and several specimens which hàve been sent to me have given way at that part of 
the body. Each segment sends off a pair of feet, which, like those of the preceding por- 
tion of the body, are composed of two branches, ventral and dorsal. The ventral branch 
is like the corresponding one of the centre feet, the two or three first being simply . 
* Th Tem 
The ventral branch, with its row of short sete, may perhaps act as a branchial organ. 
