CLASS IV. 
ANNELIDES. 
Animal with a more or less elongated body, having no 
blood, and inhabiting a testaceous tube, from which they 
never depart. 
ORDER I.—SEDENTARIA. 
Tube elongated and testaceous. 
TRIBE I.— SERPULACEA. 
Tube solid and calcareous. 
Genus I. — SERPULA. — Linneus. 
Generic Character.— Shell tubular, narrow, gradually 
widening towards the aperture, and pointed towards the 
apex ; attached irregularly to other bodies ; sometimes 
wound spirally ; keeled, imbricated, or plain; aperture 
round, for the most part, or angulated in the ribbed species. 
Serpulatricarinata, Plate V. fig. 34. 8. diphia, fig. 32. 
We have united the genera Serpula and Vermilia, there not being sufficient 
distinctive generic characters for both. They are extremely variable in form, 
and are met with in all seas. We have given an example of the expunged 
genus Vermilia, viz. V. Sulcata. Plate V. fig. 35. 
Fossil Serpule are extremely abundant, and oceur in almost all formations, 
from the newest to the Grawacke group, They are among the few shells which 
have existed through all ages to the present time. 
Genus Il. — SPIRORBIS. — Lamarck. 
Generie Character. — Shell consisting of a testaceous 
tube, spirally twisted into an orbicular form or a horizontal 
plane, depressed, and adhering below ; the aperture ter- 
minal, rounded, or angular. 
Spirorbis tenuis, Plate XI. fig. 18. 
Found in the Silurian series of rocks. 
