131 



across, bordered by pores, and disposed in five pairs, each 

 pair forming a petaloidal figure, and are then contained in 

 the form of bands to the mouth. The smaller areas are 

 contained within the petaloidal figures, and the larger sur- 

 round the ambulacra, and are extended over the rest of the 

 surface, which is covered with small tubercles, separated 

 from each other b}' distinct circlets. PL ii. fig. 6. 



Synon. jEchinobrissus, Breyn. 



Sp. 1. Cl. sinuatus. Nearly orbicular, depressed; one 

 of the larger areas is divided by a longitudinal groove, com- 

 mencing near the apex, and continued nearly to the margin ; 

 the ambulacra are bowed and broad, are transversely divided 

 by bars, leaving intervening openings, and are bordered by 

 rows of thickly set pores ; each pair of ambulacra approx- 

 imate towards the margin, and thus almost enclose the 

 smaller areas. The base is divided by five bands, pro- 

 ceeding from the ends of the petaloidal ambulacra and ter- 

 minating at the mouth ; the mouth is small and pentagonal ; 

 the vent opens laterally in the apex of the groove which 

 exists in the upper surface. 



This is the polar stone of Plott. 



No recent species of this genus is known. 



This genus is not even mentioned by Lamarck ; and the 

 first species here noticed is offered by him interrogatively, 

 as similar to galerites umbrella, with which, however, it does 

 not agree, since one of the generic characters of galerites 

 is the having of the vent placed in, or beneath and near to, 

 the margin. 



2. CL conoideus. A spathose petrifaction ; the figure 

 conoidal ; the circumference subrotund, inclining to the 

 elliptical. The divisions and situations of the areas, with 

 the structure of the ambulacra, and the nature of the sur- 

 face, point this fossil out, in the opinion of Leske, as being 

 a species of this genus. 



