EADIOLATA. 261 



and Megatrema ; his genera ISTobia and Savignium differ in 

 having but two valves for the operculum. Pyrgoma differs from 

 Creusia in having the body of the shell, i. e. the parietal cone, 

 simple, not divided into valves. PI. i. fig. 31. PL xxiv. fig. 

 489, 490. 



PTB/ULA. Lamarck. Family Canalifera, generally turbinate, 

 with few angular whorls ; aperture terminating in a canal ; colu- 

 mella smooth. The Eiculas being removed, there remain a 

 considerable number of species under this name, typified by P. 

 Melongena, &c. 



PTEUM. Humph. Pyetjla, Lam. 



PYTHINA. Hinds. Yoyage of the Sulphur. P. 70. PI. xix. fig. 

 8, 9. A bivalve shell thus described, (translation) " transverse, 



, subsequilateral, sequivalve. One valve with one small central and 

 two lateral teeth ; the other valve with two lateral teeth ; liga- 

 ment internal ; two rounded muscular impressions ; palleal 

 impression rather straight, without a sinus. There is only one 

 species described, the P. Deshayesiana. PL sxvii. fig. 571. 



QUADEATE. {Quadratus.) Square, applied when the outline 

 of shells is formed by nearly straight lines meeting at right 

 angles. 



QUINQUELOCULINA. D'Orbigny. A genus of microscopic 

 Foraminifera. 



QUOTIA. Besh. MS. Planaxis decoUatus Quoy et Gaimard. 



EADIATINGr. (Jiadians.) A term applied to the ribs, strisB, 

 bands of colours, &c. when they meet in a point at the umbones 

 of a bivalve sheU, and spread out towards the ventral margin. — 

 Ex. The bands of colour in Tellina radiata, fig. 105. 



E/ADIC ATED. {Radix, a root.) Attached, and as it were rooted 

 by means of a fibrous byssus. 



EADIOLATA. Lam. A family belonging to the dorer Cepha- 

 lopoda, Lam. The shells belonging to it are described as dis- 

 coidal, with the spire central, and the chambers radiating from 



: the centre to the circumference. This family contains the genera 

 Eotalina, Lenticub'na, and Placentula. 



EADIOLITES. A genus belonging to the family of Eudistes, 



