TEREBRATULA. 353 



mantle, which is a nearly homogeneous membrane where 

 not traversed by vessels, is simply applied to the internal 

 orifices of the cceca, and continued over them ; no trace of 

 any connection with them being visible when it is detached 

 from the shell. I may mention, however, that I have 

 found the surface of the mantle in contact with the shell 

 to be scattered over with minute cells, corresponding in 

 size and aspect with those contained in the coecal tubes. 

 " The physiological purpose of this curious structure, 

 therefore, is at present a mystery ; but there can be little 

 doubt that it is a very important one in the economy of 

 the animal, when we see the shell thus rendered subservient 

 to the special protection of these coecal appendages. ,, 



T. caput-serpentis, Linnseus. 



Subovate ; attenuated above ; whitish, co-stellated. 



Plate LVI. fig. 1, 2, 3, 4. 



Anomia caput-serpentis, Linn. Syst. Nat. ed. 12 (noted. 10), p. 1153; Fauna 

 Suecica, ed. 2, p. 521 ; Acta Upsaliens. 1773, vol. i. 

 p. 41, pi. 5, f. 3.— Born, Mus. Ca3s. Vind. p. 119.— 

 Chemn. Conch. Cab. vol. viii. p. 103, pi. 78, f. 712, 

 and vol. xi. p. 248, pi. 204, f. 2013.— Dillw. Becent 

 Shells, vol. i. p. 293.— Index Testaceolog. pi. 1 1, f. 22. 

 „ retusa, Linn. Syst. Nat. ed. 12, p. 1151 ; Fauna Suecica, ed. 2, p. 521. 



—Dillw. Becent Shells, vol. i. p. 292. 

 „ pubescens, Linn. Syst. Nat. ed. 12, p. 1153. — Schroter, Einleit. Conch. 

 vol. iii. p. 397, pi. 9, f. 10.— Dillw. Becent Shells, vol. i. 

 p. 293.— Index Testaceolog. pi. 11, f. 20. 

 „ (nov. spec), Pennant, Acta Upsaliens. 1773, p. 39, pi. 5, f. 4. 

 Terebratula pubescens, Muller, Zool. Danic. Prodromus, p. 449, No. 3007. 



„ caput-serpentis, Lam. (not Betzius), Anim. s. Vert. (ed. Desh.) vol. 



vii. p. 332. — Sowerby, Genera of Shells, Tere- 

 brat. f. 2. — Philipi>i, Moll. Sicil. vol. i. p. 95, pi. 

 6, f. 5, and vol. ii. p. G6. — Beeve, Conch. Sys- 

 temat. pi. 12G, f. 2. — Sowerby, Thesaur. Conch, 

 vol. i. pi. 68, f. 1 to 4, and pi. 72, f. 116. 

 „ costata, Lowe, Zoologic. Journal, vol. ii. p. 105, pi. 5, f. 8, 9. 



„ aurita, Fleming, Philosop. Zool. vol. ii. p. 498, pi. 4, f. 5 ; Brit. 



VOL. II. Z Z 



