ODOSTOMIA. 305 



O. ExcAVATA, PhlHppi. 



Turreted ; whorls flattish, scalar, clathrated throughout by 

 remote longitudinal and spiral costellse, of which last there are 

 four on the body, two of which are continued on the smaller 

 turns. 



Plate XCVII. fig, 3, 4. 



Bissoa excavaia, Philippi, Moll. Sicil. vol. i. p. 154, pi. 10, f. 6. 



„ Harvcyi, Thompson, Ann. Nat. Hist. vol. v. p. 97, pi. 2, f. 11. 



,, Desliayesiana, Recluz, Revue Zool. Cuvier. 1843, p. 105 ? 

 Cingula Harvei/i, Brit. Marine Conch, p. 184. 

 Purtkenia turrita. Index to Brit. Marine Conch, p. xliv. f. 91. 

 Odosiomia pupa, Searles Wood, Crag Moll. vol. i, p. 80', pi. 9, f. 5 (fossil). 

 „ excavata, Jeffreys, Ann. Nat. Hist, new ser. vol. ii. p. 345. 



Although Philippi ascribes but twelve ribs to his R. 

 excavata^ whilst about half as many again are found on 

 certain individuals of our British species, the coincidence 

 of all the other characters is so precise that we cannot but 

 regard the two shells as identical. This shell is of a 

 slightly transparent uniform white hue, is more or less 

 strong, and has a shortened turreted figure. Numerous 

 slender but rather distant longitudinal costella?, which are 

 very prominent and nearly perpendicular, continue quite 

 down to the anterior termination of the shell. These 

 upon the superior volutions are crossed by an equally 

 prominent spiral costella rather below the middle of the 

 whorl, and by a less distinct one just at the top ; two 

 additional ones encircle the body, one of them on a level 

 with the junction of the outer lip, the other about as 

 far below the last mentioned as that is distant from the 

 preceding one. There are six whorls, which enlarge 

 rather quickly than otherwise, but by no means rapidly, 

 are rather high (generally the length is only one-third 

 less than the breadth), are scalariform above, flattish or 



