208 



AuiCIIDJ!.- 



- ANNELIDA. 



-TUBICOLA. 



organs are wanting. The feet form a projecting series 

 of lobules along each side, and are all of essentially the 

 same strnctiire ; in general they consist of two branches 

 armed with bristles. These are mostly compound, and 

 in each bundle there is a spine of the usual form. In 

 the greater number of instances the feet are provided 

 with two filiform, awl-shaped cirrhi, which in some are 

 transformed into compressed laminte or leaflets. The 

 branchife are simple in structure, but their existence is 

 sometimes doubtful. They are usually in the form 

 of lobules or tonguelets placed on the feet, and dis- 

 tinguished from the true lobes of the feet by being 

 destitute of bristles or any antenna;. The Nereis 

 (Gg. 203} will illustrate this family.* 



F.4MILY v.— ARICIID.E. 



This family contains several genera, and a consider- 

 able number of species. Their body is in general 

 elongated and linear, like the Nerijides; but it is not 

 truncate anteriorly as in these worms, and is smaller 

 nearest the anterior extremity. It is usually cylindrical 

 in form, and consists of numerous short segments. The 

 head is very small, conical or rounded, in most of the 

 species possessing no antennse nor eyes. The proboscis 

 is small, somewhat membranous, and is destitute of 

 jaws. The feet are divided into two branches which 

 are not very projecting, but armed with simple seta- 

 ceous bristles. The brauchix are either wanting alto- 



gether or are very simple in their structure, exhibiting 

 the form of a setaceous or lanceolate filament reflected 

 on the back, or elongated and spreading, and frequently 

 clothed with large vibratile cilia. The species of this 

 family are miners in wet sand or mud, and are found 

 inhabiting slightly cemented sand-formed tubes. 



Families VI. and VII.— PERIPATID.E and 

 CH^TOPTERID^. 



The families Peripatidce and Chwtopteridee consist 

 each of only one genus, and only one species has as 

 yet been described belonging to each of these genera. 

 In both these families the feet are prominent and fur- 

 nished only with bristles properly so called, and there 

 is a total absence of distinct cirrhi. 



Family IX.— ARENICOLID^. 



This, the last family of the order Errantia, appears 

 to establish the passage of the animals belonging to it 

 into those of the order Tubicola; M. Savigny, indeed, 

 places them along with the Serpulcv. The Arenicoke 

 are of a cylindrical form, and the body consists of only 

 a small number of rings, but these are divided by .-» 

 multitude of transverse pleats. The head is merely 

 rudimentary, and the mouth is terminal and furnished 



Fig. 201. 



Arenicola piscatoriim, or Lu^j 



with a small retractile proboscis, but is destitute of jaws. 

 There are neither cirrhi, antennre, nor eyes. The feet 

 are uniform in structure and composed of two branches, 

 the dorsal branch being armed with simple bristles, 

 and the ventral with a series of imbedded, hooked bris- 

 tles. On a certain number of segments in the middle 

 portion of the body we find the branchise in form of 



* There are several penera belnnging to this family, as 

 Nereis, Sf/ltls, rhyllotloce Nephihys, Gli/eera, &c., &c., but tliere 

 is one whicli lias a remarl^able l^orm, and wliich has been de- 

 scribed as a new genus by tlie late Dr. Johnston of Berwick, 

 ami hitherto undescribed, which we should lij^e here particu- 

 birly to mention. He has named it Gattida, in compliment to 

 liis iVirnd Mrs. Gatty, authoress of the welt known " Paraldes 

 from Nature." It has a body consisting of about tifteeu seg- 

 ments, deeply indented at the sutures and narrowed in front. 

 Tlie small, flattened head has three long, filiform, unjointed 

 antennre, four eyes, and two pairs of tentacular cirrhi, similar 

 to the antennre. The feet are composed of only one branch, 

 and the bristles are compound and falcate. On y one species 

 bai as yet been de-cribed ; it is a native of England, and has 

 been called by Dr. Johnston Gattiula siJCetabUis. 



well developed arbuscles. The figure we here give 

 (^Arenicola piscatorimi) will give a good idea of the 

 family.— See fig. 204. 



Order II.— TUBICOLA or SEDENTARIA 



(= Capiiibranchieda) . 



The Annelides of this order are so called from the 

 great majority of them living in tubes, which, from the 

 organization of their bodies, they are incapable of leav- 

 ing. They are hence also named sedenlai-y animals, 

 as the tubes they inhabit are frequently permanently 

 fixed. The body of the animals is worm-shaped, cylin- 

 drical, generally swollen or thickened on the anterior 

 portion, while the posterior is smaller, of less diameter, 

 and sometimes distinctly defined as a bristleless appen- 

 dage. It is composed of numerous short segments; 

 the head is ill defined, not distinguishable from the 

 anterior segment which contains the mouth ; and there 



