238 



ANNELIDA. 



Serpula. 



Genus III.— CLITIA.— Leac^. 



Shell, a depressed, irregular-sliaped cone, attached hy the 

 base, and consisting of four unequal, dissimilar valves, two 

 larger and two smaller, laterally united by the interlocking of 

 their dentated 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. Clitia verruca.— The Wart-like Clitia, pi. XCVII. fig. 

 61, 61*. 



C. Verruca. Brown, 111. Kec. Couch. 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. 



rounded oval, and interiorly funnel-shaped ; operculum, with 

 four obtuse valves. 



1. CoEONULA DiADEMA. — The Crown-shapcd Coronula, pi. 

 XCVII. fig. 47, 48. 



Donovan, Brit. Sh. pi. 56. 



Somewhat compressed, with sbc prominent longitudinally 

 ribbed valves ; alternating with as many transversely striated 

 ones. 



The Red Crag, Sutton. 



Genus Y.—AGIDASVIS.—Murchison. 



AciDASPts Beightii. — Bright's Acidaspis, pi. XCVII. f. 65. 

 A. Brightii. Murchison, Sil. Syst. p. 658, jjI. 14, fig. 15. 



Genus VI.— AGNOSTUS.— Brow^/niarte. 



Genus IV.— CORONULA.— Lajnar-cfc. 



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 



1. Agnostus pisifohmis. — The Fish-shaped Agnostus, pi. 

 XCVII. fig. 64. 



A. pisiformis. Murchison, Sil. Syst. p. 664, pi. 25, fig. 4. 



2. Agnostus Tuberculatds. — The Tuherculated 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.— SEDENTARIA. 



Tube elongated and testaceous. 



Tribe I.— SERPULACEA. 

 Tube solid and calcareous. 



Genus I. — SERPULA. — Linnceus. 



Shell tubular, narrow, gradually widening 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, Blackdown. 



2. Serpula caeinella. — The Small-keeled Serpula, pi. 

 XCVIII. fig. 7. 



