364 MALENTOZOA. SESSILIA. 



B. Bdlanus elongatus angulosus. 



Shell cylindrical, subangular ; the valves united, separating 

 at the top, and running out into thin, more or less acute points ; 

 the opercular valves striated, rather obtuse, with the sinuosities 

 of their junction apparent. 



C. Bdlanus elongatus fistulosus. 



Shell cylindrical, subangular, the valves united, separated 

 toward the end, which is much wider than the base ; the oper- 

 cular valves rather obtuse, thick, with the striae obsolete. 



D. Bdlanus elongatus clavdtus. 



Shell very elongated, narrow at the base, cylindrical or en- 

 larging upwards, at the end much expanded, or cup-shaped, 

 or clavate, with the valves separated, thin-edged, rounded or 

 acute ; opercular valves thin, distinctly striated, elongated, 

 divaricate, and more or less pointed at the end. 



It occurs profusely on piles and stakes, as well as on rocks, 

 stones and shells. It is the most common species on the stakes 

 of the salmon nets from Aberdeen to Newburgh; on the stones 

 at Don-mouth, and the Black Dog stone. 



Lepas elongata. Gmel. Syst. Nat. 3213. — Lepas balanoides, var. 

 Penn. Brit. Zool. iv. 72. PI. 37. f. 5. — Balanus clavatus. Mont. 

 Test. Brit. 10. — Balanus rugosus. Mont. Test. Brit. 8. — Lepas 

 elongata. Chemn. Conch, viii. PI. 98. f. 838. — Balanus fistulosus. 

 Larak. Syst. v. 396; Ed. 2. vi. 665. — Balanus rugosus. Brown, 

 Illustr. PI. 6. f. 6. PI. 7. f. 1 , 2, 3, 4, 20.— Balanus fistulosus. 

 Brown, Illustr. PI. 7. f. 21. 



6. Bdlanus cdndidus. White Acorn-Shell. 



Shell conico-cylindrical, with the six thin valves distinct, 

 separated by wide depressed areas, which are longitudinally 

 striated ; the elevated areas transversely rugose or striate, and 

 longitudinally striulate ; the aperture very large ; the ventral 

 opercular valves transversely sulcate and longitudinally striu- 

 late, acute ; the dorsal transversely striate, and longitudinally 

 sulcate toward the suture-margin, in which is a groove, to re- 

 ceive the ventral valves ; a space bounded by two sulci running 

 out at the base into a prominence ; the hind part of the base 

 sloping rapidly upwards ; the tip acute. Internally, the shell 

 is continuous, and longitudinally striated. The individual 

 described is white, with a delicate greyish-yellow epidermis ; 

 its diameter at the base an inch and four-twelfths, its height 

 ten-twelfths. 



