TUB[COL.i!;. 



3[)] 



sliders them as the intermediate link between the Vertebrata and Annulosa, ob- 

 serving upon the curious circum- 

 stance that these two subkingdoms, 

 so highly organized in the scale of 

 the creation, should be linked to- 

 gether by a group exhibiting such 

 great imperfections of structure. 

 This class has been greatly neg- 

 Dr. Johnston has, however, described various species (especially 

 in the Annals of Natural History, for February, 1840), and Mr. Mac Leay, in the same 

 number,* has noticed several fossil species. It is, however, in France that the greatest 

 attention has been paid to them, especially by Savigny, Audouin, and Milne Edwards.] 



lected in this country. 



THE FIRST ORDER OF ANNELIDES. 



THE TUBICOLyE. 

 Some species of this division form a homogeneous, calcareous tube, which probably results 

 from their transudation, like the shells of the Moliusks, but to which the muscles do not adhere ; 

 others construct tubes, by agglutinating grains of sand, fragments of shells, and particles of 

 mud, which tliey join by means of a membrane, which likewise is doubtless transuded ; lastly, 

 there are some, the tubes of which are entirely membranous, or horny. 



To the first group belong 



Serpula, Linn., — 

 The calcareous tubes of which hivest, from their twisting about, fragments of stones, shells, and all sorts of 

 submarine matters. The truncation of these tubes is either round or angular, according to the species. 

 The animal within has its body composed of a great number of segments ; its fore-part widened 

 into a disk, furnished on each side with many bundles of stiff bristles ; and on either side of its 

 mouth is a tuft of fan-like gills, in general vividly coloured. At the base of each tuft is a 

 fleshy filament ; and one of these, on the right or left side indifferently, is always prolonged and di- 

 lated at its extremity into a variously-formed disk, which serves for an operculum and mouth at the 

 entrance of the tube when the creature retires into it. 



The common species (S. contortupUcata, Ellis), has a round and twisted tube three 

 lines in diameter. Its operculum is funnel-shaped, and its gills often of a line red, or 

 varied with yellow, violet, &c. This animal quickly fabricates its tube of mud, agg-luti- 

 nating into it whatever small objects lie around. 



There is another and smaller species on our coasts, with a club-sliaped operculum, 

 armed with two or three little points (S. vermUularis, Gmelin). Its gills are sometimes 

 blue. Nothing- is more beautiful to see than a group of theic SerpuhT when their wings 

 are expanded. 



In other species, the operculum is flat, and bristled with more numerous points. 



These are the Galeolaria, Lamarck. 



There is one in the Antilles {.5. giyaiitea, Pallas), which is found among the Madre- 



rtupiicnta, pores, and the tube of which is often inclosed in their mass. Its gills roll up spirally 



when they are withdrawn, and the operculum is armed with two little branching horns 



Mr. Mac Lcny has given tlie following quinari.tn distribution of tlie class in the memoir noticed al)o 



the 



NOBMAL GkO 



Pfllt/pOiift. 



IMarine animals, havi 



provided with distinct feet. 



AoKaKANT Gboup. 



yfpoda. 



liody without feet, or a 

 h.-ad. 



. , f Nercidina. 

 (_ Scrpuhna. 



ribution of the class 

 ANNELIDA. 



mals free, having a distinct head, provided with eyes, oi 

 mals sedentary, and havin;; no heaii, provided with eyes 



body externally setigerc 



ntenntc, or both. 



limals without eyes or antcn 

 ;iou distinct. 



linials aquatic, without eyes 

 ndistinct. 



iinials provided generally w 

 nicuhttion distim-l 



)us for locomotion ; articula- 

 aiueiino: ; bony not externally setigemus ; articulation 

 eyes, but not with antcnntc ; body not externally seli- 



ge 



