BALANIDEA. 81 



a genus on grounds so slight, I have simply transcribed the 

 description given above, leaving others to form their own con- 

 clusions as to the propriety of separating this shell from the 

 genus BuKnus. Britain, Central and Southern Europe. Azeca 

 Tridens, PI. xiv. fig. 290. 



AZEMTJS. Eanzani. Conia, Leach. 



BACULITES. Lam. Fam. Orthocerata, Bl. Ammonacea, Lam. — 

 Bescr. Straight, conical, tubular, laterally compressed ; chambers 

 divided by very sinuous lobed septa, the last elongated ; aperture 

 elliptical; siphon dorsal. — Obs. This genus differs from Ortho- 

 ceras in the same manner in which Ammonites differs from 

 Nautilus, having its septa sinuated and branched. A Baculite 

 might be described as a straight Ammonite. This genus is known 

 only in a fossil state. It is found in the Cretaceous Limestone 

 of Maestricht and Yalognes. B. Eaujasii. PI. xxiii. fig. 484. 



BALAJSTTTS. Brug. (an Acorn ; " gland de Mer." Er.) Order Sessile 

 Cirripedes, Lam. Fam. Balanidea, Bl. — Bescr. Shell composed 

 of six valves articulated to each other side by side in a circle, by 

 the insertion of lamina ; closed at the base by a flat, cylindrical 

 or cup-shaped valve, by which it is generally attached ; and at 

 the apex by a conical operculum, consisting of four valves in 

 anterior and posterior pairs. Each valve of the shell is divided 

 iuto a rough triangular portion pointed towards the apex, and a 

 flat area on each side. — Obs. This description includes the Acasta 

 of Leach, which growing in sponges, has the base cup-shaped ; 

 Conoplcea of Say, which being attached to the stems of Grorgonia 

 and sea- weeds has the base elongated and lanceolate, and Chirona, 

 Gray. Balanus is the only genus of Sessile Cirripedes the shells 

 of which consist of six parietal valves, except coronula, which has 

 no sheUy base, is flatter, and has the valves of the operculum 

 placed horizontally. The Balani are common in all seas, ad- 

 hering to rocks, corals, floating timber, and to each other. The 

 fossil species are found in the newest strata, at Bordeaux, Paris, 

 &c. Eig. 25. B.Tintinnabulum ; 26. AcastaM.o\dvi^\ ; 27. Balanus 

 galeatus, Conoplwa, Say. PI. i. figs. 25 to 27. 

 BALANIDEA. Bl. The second family of the class Nematopoda, 



