16 ORDER I. SESSILES. 



at the top. This singular Lepas is found imbedded in the skin and fat of 

 the South Sea whale, which it penetrates in clusters. 



Example. 



PI. I. Fig. 1 to 3. 



Tubicinella bal^enarum, Lamarck, Ann. du Mus., vol. i. p. 461 . pi. 30. 



f. 1. 

 Lepas tracheaformis, Linnaeus. 

 Coronula tubicinella, De Blainville. 



CORONULA, Lamarck. 



Testa suborbicularis, obtuso vel compresso-conoidea, valvis sex insequa- 

 libus lateraliter ferruminatis composita ; extremitate inferiori trun- 

 cata, superiori operculo quadrivalvi membranaque clausa, valvis 

 operculi obtusis, parietibus crassissimis intiis plerumque cellulis 

 radiantibus excavatis. 



The shell of Coronula differs from that of Tubicinella in being of a 

 more compressed form, never thickened at the margin, and consequently 

 not encircled with transverse ribs. The substance of the longitudinal 

 valves is internally divided into a number of radiating cells, or into 

 irregular distorted ramifications. Some naturalists have formed distinct 

 genera of these varieties ; for instance, Dr. Leach his Chelonobia, and 

 Klein his Polylopos and Astrolepas ; we must consider them, however, 

 but as species, adhering to the original arrangement of Lamarck. 



Examples. 



PI. II. Fig. 1. 



Coronula diadema, Lamarck, Anim. sans vert., vol. v. p. 387. 

 Lepas diadema, Linnseus. 

 Polylepas diadema, Gray. 

 Polylopos balcenaris, Klein. 



