238 
ANNELIDA. 
Serpula. 
Genus III.—CLITIA.— Leacli. 
Shell, a depressed, irregular-shaped cone, attached by the 
base, and consisting of four unequal, dissimilar valves, two 
larger and two smaller, laterally united by the interlocking of 
their deutated margins; aperture somewhat trapeziform, late¬ 
rally placed, and entirely filled by a bipartite operculum, one 
of the pieces of which is irrregularly quadrate, and the other 
nearly triangular. 
1. Clttia verruca. —The Wart-like Clitia, pi. XCVII. fig. 
61, Gl*. 
C. Verruca. Brown, Ill. Rec. Conch. Brit. p. 122, pi. 53, 
fig. 30. 
Much depressed, compartments strongly ribbed diagonally, 
and oblique to each other, and finely striated transversely; 
margin of the base irregularly serrated; aperture quite closed 
by the operculum. 
The Red Crag, Walton, Coral Crag, Sutton, and Raised 
Beaches, Clyde, &c. 
Genus IV.—CORONULA.— Lamarck. 
Shell seated, sub-orbicular; valves apparent, indivisible, 
conoidal; with very thick walls, and interiorly hollowed in 
radiating cells, eighteen in number; aperture regular, of a 
rounded oval, and interiorly funnel-shaped; operculum, with 
four obtuse valves. 
1. Coronula diadema. —The Crown-shaped Coronula, pi. 
XCVII. fig. 47, 48. 
Donovan, Brit. Sh. pi. 56. 
Somewhat compressed, with six prominent longitudinally 
ribbed valves; alternating with as many transversely striated 
ones. 
The Red Crag, Sutton. 
Genus V.—ACIDASPIS.— Murchison. 
Acidaspis Brigvitii. —Bright’s Acidaspis, pi. XCVII. f. 65. 
A. Brightii. Murchison, Sil. Syst. p. 658, pi. 14, fig. 15. 
Genus VI.—AGNOSTUS.— 
1. Agnostus pisiformis. —The Fish-shaped Agnostus, pi. 
XCVII. fig. 64. 
A. pisiformis, Murchison, Sil. Syst. p. 664, pi. 25, fig. 4. 
2. Agnostus Tuberculatus. —The Tuberculated Agnostus, 
pi. XCVII. fig. 66. 
A. Tuberculatus. Murchison, Sil. Syst. p. 604, pi. 3, fig. 
17,17a. 
CLASS FOURTH. 
ANNELIDA. 
Animal with a more or less elongated body, having no blood, 
and inhabiting a testaceous tube, from which they never depart. 
ORDER I.—SEDEXTARIA. 
Tube elongated and testaceous. 
Tribe I.—SERPULACEA. 
Tube solid and calcareous. 
Genus I.—SERPULA. — Linn ecus. 
Shell tubular, narrow, gradually wideniug towards the aper¬ 
ture, 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. 
1. Serpula plexus. —The Woven Serpula, pi. XCVIII, 
fig. 8. 
S, plexus, Sowerby, VI. p. 201, pi. 598, fig. 1. 
Cylindrical, smooth, greatly curved, much interwoven into 
masses ; tube diminishing gradually. 
The Upper Chalk, Norwich, the Lower Chalk, Dover, and 
the Greensand, Blaekdown. 
2. Serpula caiiinella. —The Small-keeled Serpula, pi. 
XCVIII. fig. 7. 
