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478 DR. BAIRD ON A NEW SPECIES OF BRITISH ANNELIDES. 
"The worms of which this family (the Ariciidee) is composed are distinguished by 
MM. Audouin and Milne-Edwards as possessing slender elongated bodies, by their head 
being rudimentary, by the want of antenne and tentacular cirri, by their branchis 
being either absent or, when present, very simple, and by their feet being dissimilar in 
different parts of their body. They have no eyes, no jaws, a very small and indistinct 
proboscis or pharynx, and in general a single cirrus to each foot. 
In Grube's and Oersted’s arrangements a series of. genera, which were not known to 
MM. Audouin and Milne-Edwards as natives of the coast of France, are introduced, which 
possess long tentacular cirri, frequently two pairs of eyes, more distinct branchiz, and on 
some parts of the body a series of hooked bristles like what we always find existing in the 
Capitibranchiate or Tubicolous Annelides. Oersted, in consequence of this diversity of 
form, divided the Ariciide into two groups, which he named Aricieze verze and Aricieæ 
naideze. Grube, in his * Familien der Anneliden,’ published in 1851, follows this arrange- 
ment, retaining the large family Ariciidæ, divided into two sections; but Sars considers 
that these two sections must be raised to the rank of distinct families, and in this view he 
has been followed by Carus in the ‘ Handbuch der Zoologie,’ a work a part of which only 
has been published last year (1863)*. It is to the latter section, the Aricieze naidew of 
Oersted, the Spioneæ of Sars, that the species of Chetopterus show the greatest resem- 
blance. If we examine the figure of any of the species belonging to the genus .Leucodore, 
and more especially to Disoma, the resemblance in form will be seen at once. (See the 
figure of Disoma multisetosum in Wiegmann’s ‘ Archiv,’ 1844, tab. 2. fig. 1.) 
The family Chzetopteridee now consists of two genera, Chetopterus and Spiocheto- 
pterus, and only a few species have as yet been enumerated. Spiochetopterus contains 
only one, while Chetopterus possesses six. One of these, Ch. pergamentaceus, Cuvier, 
Is a native of the seas of the West Indies; a second, Ch. norvegicus, is from the coast 
of Norway; two have lately been described by Stimpson as occurring, one at Simon’s 
Bay, Cape of Good Hope, the other at Port Jackson, Australia; and two others have 
been described by Schmarda (perhaps identical with those of Stimpson), one of them 
being found in Simon's Bay, Cape of Good Hope, and the other in Australia. A seventh 
spectes has, more recently still, occurred to me as a native of our own shores, a species 
which is very interesting as showing a nearer approach to the genus Spiochetopfíerus, 
and consequently to the Spionide, than any yet noticed. This species 1 shall now 
proceed to describe. 
CH#TOPTERUS INSIGNIS, Baird. (Plate XLIX. figs. 1 & 2.) 
The three parts into which the body of the animal may be distinguished are very 
distinct, The anterior portion (Pl. XLIX. figs, 1 & 2, a) is square-shaped, broad, flat- 
tened or slightly convex on the ventral surface, and somewhat concave on the dorsal, 
and 15 composed of eleven segments. The first is the buccal segment, forming the head, 
. . ا : * 
pee 5i his Neue wirbellose Thiere,’ published in 1861, adopts another arrangement. He places m 
ind - Foie in the — Abranchia, which consists, according to him, of two divisions :—1. Achaeta, CoP- 
and Peripatide ; 2. Chsetophora, containing the Lumbricide, Naidide, Tomopterid,‏ — : الج 
æ, and, lastly, the Cheetopteridee. This arrangement appears as faulty as Cuvier's or Grube's‏ 
É— cm 
