172 SESSILIA. 



lete striae. Two inches broad at the base. Inhabits the 

 Frith of Forth. 



Genus 6 CORONULA Lamarck, 



Generic Character Body sessile, enveloped in a shell, 



with small setaceous and cirrous arms Shell sessile, sub- 

 orbicular, conoid, or conically truncated at the extremities, 

 with very thick walls, and interiorly hollowed in radiating 

 cells; aperture regular, of a rounded oval, and interiorly 

 funnel-shaped ; operculum having four obtuse valves. 



Coronula diadema. — The Crown Coronula. Plate 

 XIX. fig. 12. Somewhat compressed, with six prominent 

 longitudinally ribbed valves ; alternating with as many de- 

 pressed transversely striated ones. Found attached to the 

 skin of whales in the North seas. 



Genus 7.— TUBICINELLA— Zama/cA. 



Generic Character. — Body enclosed in a shell ; with 

 small setaceous and unequal cirri. — Shell univalve, tubular, 

 straight, somewhat narrowed towards the base; surrounded 

 with nearly equidistant transverse ribs ; truncated at both 

 ends, open at the top, and provided with an operculum, con- 

 sisting of four valves ; base closed by a membrane. 



Tubicinella balcenarum. — The Whale Tubicinella. 

 Plate XIX, fig. 13. Tubular, with transverse ribs, and a 

 ring-shaped margin ; operculum bottle-shaped. Found buried 

 in the fat of the skin of whales in the American seas, — the 

 operculum, and a portion of the upper part of the tube only 

 being visible. 



The Ciiripeda differ so much in structure from the MoUusca, that 

 they form a perfectly distinct group, intermediate between them and 

 the Crustacea, or perhaps more nearly allied to the latter. Although 

 in this arrangement they are not included among the Articulata, it is 

 obvious that they correspond with them to a great extent, as they have 

 their arms or filaments jointed. Some testaceous shells occurring in 

 that great division of the animal kingdom, it has been judged proper 

 to give some account of them in the following pages. 



