1054 PATELLA. 



or less slightly sinuated ; the colour is generally whitish, with 

 the summit pale yellow, and the inside either yellow or 

 brownish, and finely striated with raised dots. Linnseus has 

 figured this shell in the M useum Tessinianum, and appears 

 to have been at a loss whether it should be considered as a 

 shell or an operculum. Lamarck supposes that it is a single 

 valve of a species of his Genus Acardo, which he defines to 

 be composed of two flat nearly equal valves, without either 

 a hinge or cartilage, and with a muscular impression in the 

 center of each. 



tF ^ ^ w W 



* JVitfi a marginal Jissure. 



FLSSURA. 87. Shell conical, cancellated, with a 

 deep and narrow marginal fissure, and the 

 summit recurved. 



Patella Fissura. Limiaus Syst. ISIat. p. 126 1. Martini, i. 

 p. 145. 1. 12. f. 109 and 1 10. Pennant Zool. iv. p. 144. 

 t. 90. f. 152. Da Costa Brit. Conch, p. 1 1. t. 1. f. 4. 

 Born Miis. p. 427. t. 18. f. 12. Schroeter Einl. ii. 

 p. 434. MuUer Zool. Dan. i. p. 25. t. 24. f. 7 to 9- 

 Gmelin, p. 3728. Schreibers Conch, i. p. 362. Dono- 

 van, i. t. 3. f. 2. Montagu Test. p. 490. Maton and 

 Racket, in Lin. Trans, viii. p. 235. Dorset Cat. p. 59. 

 t. 23. f. 4. Brookes s Introd. p. 138. t. 9- f. 127- 

 Emarginula conica. Lamarck Syst. des /Inim. p. 69- 

 Le petit Cabochon I'Entaille. Favanne, i. p. 548. t. 4. 



f.M 1. 

 Lister Conch, t. 543. f. 28. Petiver Gaz. t. 75. f. 2. 

 Inhabits the coasts of Great Britain. Lister, S^c. Algiers. 



Linnaous. 

 Shell five, or sometimes six lines long, and the height and 

 breadth are each about equal to three-fourths of the length ; 

 it is white or brownish white, and elegantly cancellated with 

 longitudinal ribs and transverse striae; the fissure extends 

 from the margin about one-third of the way t® the summit, 

 and is very narrow. D'Avila calls this a fresh-water shell, 

 and says it inhabits the Lake of Geneva, but this is most 

 probably a mistake. 



INCISA. 88. Shell oval, rather depressed, cancel- 

 lated, with a broad marginal fissure, and the 

 summit recurved. 



