236 AMPHITKITE. 



PLATE XXX. 



FIG. 3. Antennulse, natural size. 



4. Regenerating plume from a stump within the tube. Trowels, a, b, 



clasping the edge of the orifice. Scoop or tongue between them, c. 



5. Young specimen in a perfect tube. Branchiae or funnel, a. 



6. Another. 



7. Young specimen with seven branchiae. 



8. The same, enlarged. 



9. Fragment, which separated from the posterior extremity of an adult, 



regenerating a branchial plume, a ; secretory glands, b. 



10. The same enlarged. 



11. The same, with the plume regenerated slightly, enlarged. 



2. AMPHITRITE BOMBYX. Plate XXXI. Figs. 1, 2, 3, 4. 5. 



The general structure of this animal resembles that of the preceding 

 subject, in a luxuriant plume of branchiae crowning a vermicular body, 

 and in dwelling in a sheath. 



Its name is derived from the materials whereof the sheath is formed, 

 being an animal gluten like silk, without earthy particles incorporated 

 during its fabrication. 



The total length of the Amphitrite is about three inches, or little 

 more, whereof the plume, composed of towards sixty branchiae, consti- 

 tutes a third, and the body, equalling two-thirds, consisting of sixty or 

 seventy segments, is terminated by two white papillae. 



The shoulder enlarges as a marginal white frill, from which the 

 plume originates ; and each side of the body is bordered by a row of 

 short bristly pencils, with a black speck near the roots. A groove com- 

 mences at some distance from the frill towards the belly ; and within the 

 frill the neck of the plume, which is white, is encircled by a row of very 

 dark lines. Plate XXXI. figs. 1, 2. 



The branchiae of the plume are disposed in lunate arrangement, like 

 those of the Cristatella. They bear a narrow resemblance to feathers, 

 each consisting of ribs bordered by a double row of active cilia, alike 

 numerous, and longer in proportion than those of the preceding species, 



