THE SEEPULIN2E. 



239 



principles to the attached end of each hook. By the aid of these, the Serpulae very cleverly withdraw 

 themselves with lightr.ing-like rapidity on alarm. "These organs are formed on the model of a 

 Ledger's bill hook, only that the edge is cut into long teeth. Carefully counting them, I have found 

 that each Serpula carries about 1,900 such hooks on its corselet, and that each of these being cut into 

 seven teeth, there are between 13,000 and 14,000 teeth employed in catching the lining membrane of 

 the tube, and in drawing the animal back." The branchiae consist of most elegant comb-like filaments, 

 richly coloured, arranged in two rows around the front extremity, one row on each side of the mouth. 

 They are graduated in length, and are so affixed that, where the rows meet behind, they can be 

 thrown in, so that a vertical view of 

 the circular coronet shows a great sinus 

 in it. These brilliant gill-tufts form 

 the most attractive feature in these ele- 

 gant worms, and are individually most 

 exquisite examples of mechanical con- 

 trivance. Examined under a low micro- 

 scopic power, they present a most 

 charming spectacle. Each filament con- 

 sists of a pellucid, cartilaginous stem, 

 from one side of which springs a double 

 series of secondary filaments, like the 

 teeth of a comb. Within both stems 

 and filaments the red blood may be seen 

 with beautiful distinctness, driven 

 along the artery and back by the veins 

 (which are placed close side by side), in 

 ceaseless course, contributing a very 

 striking spectacle. The exterior of 

 these organs is set with strong cilia, 

 so arranged that the water-current is 

 vigorously driven upwards along one 

 side of the filament, and downwards 

 alonij the other." This current brings 



o o 



the food destined for the nutrition of 



the animal into the funnel formed by 



the branchiae, at the bottom of which 



is the mouth, along with a quantity of water, which, again, is expelled by means of a ciliated lining 



of the hinder p<rts in a strong current impinging against the closed end of the tube, and which 



carries with it all extraneous or faecal matters. (Gosse). 



Protula dysteri is a many-segmented form, and its delicate tube is white, calcareous, more or 

 less wavy, and attached to a solid body by one end. Rising from a fixed base, these worms unite 

 together side by side in irregular bundles, which leave spaces here and there between the tubes like a 

 solid network. Each tube has a circular section, is thickened at intervals, and obscurely annulated. 

 When active, the Protulse issue from the tubes, and each spreads out its eight branchial filaments and 

 displays its red cephalic end. Another species, with the tube about five or six inches long and about 

 the thickness of a goose-quill, is very cautious, and will remain in its tube for hours without 

 projecting its branchial tufts; but when they are slowly put forth, and then expanded, their beauty is 

 extreme. On the slightest vibration of the water the worm retreats. This worm has no 

 operculum, and the genus has a vast range, being found in the Mediterranean, the Atlantic, and 

 West Indies. Huxley has shown that when the Protula attains a certain length, all the segments 

 behind the sixteenth become separated as a new zooid, by the conversion of the seventeenth segment 

 into a head antl fore part, as in Syttis prolifera. 



The clredgings in the North Atlantic yielded many small tubular shells, slightly curved and open 

 at both ends. One end is wider than the other, and the whole may be from one to two inches in 



SERPULA VEHMICULARIS. 



