LEPAS. 37 



TURTLE ACORN. 

 PI. 5. /. 4. Mrs. Robinson. 



4. Lepas testudinaria. L. testa plano-convexa } radiis sex excavatis 



striatis. Linn. Syst. Nat. p. 1108. Linn. Gmel. p. 3209. 

 Shell plano-convex, with sixjhollow, striated, rays. 

 Lepas testudinaria, testa suborbiculari, plano-convexa Icavi, intus lamellis 



serrulatis, areis excavatis transverse sulcatis. Born, Mus. Cees. p. 5. 



— ejusd. Testae. Mus. Cces. p. 10. 

 Balanus ovatus, subdepresso conicus, sulcis sextriquetris excavatis, 



superne stellatis. Gron. Zooph. Fasc. 3. p. 257. 

 Verruca testudinaria. Humph. Mus. t. 40. f, K. 

 Ellis, Phil. Trans, vol. 50. t. 34. f. 12. Gault. Test. t. 106. f. M. N. O. 



Knorr. Vergn. 3. t. 30. f. 3, 4. Favanne, t. 59. f. A. 4. A. 5. Chem. 



Conch. 8. t. 99. f. 847, 848. Encyclop. Method, pi. 165. f. 15, 16. 



This shell is of an oval shape, and convex ; the sur- 

 face is white, smooth, and composed of six uniform tri- 

 angular valves, which are separated from each other by 

 as many excavated rays ; these rays are striated trans- 

 versely, and sometimes grooved in the same direction. 

 The opening in the upper surface of the shell is oval, 

 and partly closed by a quadrivalve, convex operculum, 

 connected by ligament. The shell beneath, in its recent 

 state, according to Plancus, has a coriaceous membrane, 

 which supplies the place of the testaceous base, with 

 which the conical species are, for the most part, provi- 

 ded. This membrane is never preserved in cabinet spe- 

 cimens. The opening of the shell beneath is much 

 larger than above, and the thick walls are formed of 

 numerous vertical laminae, radiating from the centre 

 towards the circumference. These laminae are striated 

 on both sides, and finely serrated on the edge. The 

 specimen figured in pi. 5, is a young shell, and is there- 

 fore without those indentations on the edges of the exca- 

 vated rays, which occur in those of more advanced age. 



