380 PTEROrODA. 



H. trispinosa, Lesueur. 



Plate U, fig. 3. 



Davila, Cat. Cabinet, vol. i. pi. 20, f. e, ? 

 Chemn. Conch. Cab. vol. viii. p. 65, vignette 13, f. c. d. 

 Hyalea trispinosa, Lesueur, MSS. in Blainv. Diet. Sc. Nat. vol. xxii. p. 82. — 

 Thompson, Ann. Nat. Hist. vol. v. p. 13; Report Brit. 

 Assoc. 1843, p. 249. — Quoy and Gaym. Voy. Astrol. vol. 

 vii. p. 378, pi. 27, f. 17, 18, 19.— Desh. Encycl. Method. 

 Vers, vol. ii. pt. 2, p. 310 ; Lam. Anim. s. Vert. vol. vii. 

 p. 417, 421.— Cuv. Regne Anim. (ed. Griffith) pi. 3, f. 7. 

 — D'Orbig. Moll. Cuba, p. 81. — Philips, Moll. Sicil. 

 vol. ii. p. 71. 

 „ mucronata, Quoy and Gaym. Ann. Sc. Nat. vol. x. p. 231, pi. 8, 13, f. 



1.2! (fide Desh.) 

 „ triaeantha, Guidotti, in Bronn Ital. p. 85 (fide Philippi), fossil. 

 „ depressa, Bivona, teste Philippi, Moll. Sicil. vol. i. p. 101, pi. 6, f. 19, 

 fossil. 

 Hyaks a trots pointes, Chenu, Traite Elem. Conch, p. 125, f. 403, 404. 



The only indigenous example of this fragile shell having 

 inadvertently been crushed, our description has necessarily 

 been derived from foreign examples, one of which was the 

 specimen sent to us by Mr. Robert Ball as identical with 

 the individual, from whose discovery by himself, the species 

 has been introduced into the British Fauna. 



The shell is of a more or less transparent white, partially 

 stained with brown or vinous red, especially near the lips, 

 and at the commencement of the tail. It is depressed, 

 straight (not curved), and kite-shaped : the anterior extre- 

 mity, or the portion above the short, but very acute, lateral 

 spines, one of which runs out nearly at right angles, or with 

 a slight descending inclination, to the body on each side of 

 it, is much shorter than the posterior end ; the latter is 

 produced into a very long and slender straight caudal spine, 

 which, however, is very rarely procured in an unbroken 

 state. The labial aperture is short, narrow, and semi- 

 elliptic, the marginal fissure, which extends to the tips of 



