from the Island of Malta. 275 



anterior and posterior, are short, and the central one is long, 

 forming an arch over the whorl ; the posterior, at their junc- 

 tion with the central curve, form angles, from whence blunt 

 spiny processes proceed; these form a conspicuous ridge on 

 the posterior upper part of the whorls ; the junction of the 

 anterior with the central curves forms a carina on the body- 

 whorl, which commences at the posterior border of the aper- 

 ture, and terminates at the anterior part thereof, at a dis- 

 tance from the umbilical ridge. The longitudinal elevations 

 form a kind of cellular structure ; between the plates they are 

 seven or eight in number, and on them and the intervening 

 surface of the shell, delicate longitudinal lines are sculptured. 

 The aperture is entire, and is round or inclining to an oblong. 



Dimensions. — Length 2y% inches, diameter of the body- whorl 

 ^^ths of an inch. 



Collected from the calcareous sandstone No, 4, at Malta. 



Lenticulites complanatus, Defrance. PI. YII. fig. 4«, b. 



Genus Lenticulites, Lamarck. (Subkingdom Radiata. 

 Class Foraminifera, Order Helicostegues, D'Orb. Family Nau- 

 tiloida.) — Shell nautiloid, equilateral, spire rolled on the same 

 plane, compressed, sublenticular, multilocular ; whorls apparent, 

 opening narrow, triangular, prominent, against the penultimate 

 turn of the spire. 



Diagnosis. — Shell oblong, lenticular, much compressed; septa 

 convex, with longitudinal partitions, growth lines very appa- 

 rent. Long diameter j^^ths of an inch. 



This beautiful Foraminiferous shell occurs in great abundance 

 in No. 3, the yellow sand with blackish grains; in fact it forms 

 large masses of rock in this bed. As it is constantly associated 

 with the Echinoderms, we have added a drawing thereof. De- 

 france noticed, but did not figure this fossil ; he collected it at 

 "Anvers pres de Pontoise, h Dax, k Loignan pres de Bordeaux, 

 k Boutonnet pres de Montpellier, et en Italic dans les couches, 

 qui paroissent appartenir au calcaire coquillier grossier*." 



EXPLANATION OF PLATES IV. V. VI. and VII. 

 Plate IV. 



F^ff. 1. Cidaris Melitensis : a, the upper surface; 6, side view of the am- 

 bulacral and interambulacral areas, natural size ; c, an interam- 

 bulacral plate, and a portion of an ambulacral area with the 

 poriferous zones, magnified. 



* Diet. Sc. Nat. tome xxv. p. 453. 



18* 



