I30 TABULATE CORALS. 



those assigned to A. Labechei (" somewhat more than one-third 

 of a Hne "), while in other parts the long diameter of these open- 

 ings is that of A. Grayi (" about half a line "). Moreover, thin 

 sections show that they agree with one another in their internal 

 structure, this exhibiting a feature unusual in the genus Alveo- 

 lites — namely, a well-developed system of septa. These septa 

 are excellently seen by means of thin tangential and vertical 

 sections (PI. VI., figs. 3-3 a), and have the form of a circle of 

 radiating spines, of variable number (often ten or twelve), ex- 

 tending into the interior of the tubes, and sometimes reaching 

 nearly to the centre of the visceral chamber. In longitudinal 

 sections (PI. VI., fig. 3 a) these septal spines are seen to form 

 vertical rows, and to be generally markedly directed upwards, 

 or towards the mouths of the tubes. Owing to this latter fact, 

 they often look, when seen in transverse sections (PI. VI., fig. 3), 

 as if they were not actually connected with the wall of the tube. 

 Longitudinal sections show the presence of numerous complete 

 tabulae, and occasionally of mural pores, the latter seemingly 

 more numerous and smaller than is usual in Alveolites. Both 

 kinds of sections show that the walls of the corallites are in no 

 wise abnormally thickened, and ^. Labechei, E. and H., is thus 

 shown to belong properly to Alveolites as here understood. 



Formation and Locality. — Abundant in the Wenlock Lime- 

 stone of Benthall Edge, and Dormington Quarry near Stoke- 

 Edith. Also in the Wenlock Limestone of Gotland. It has 

 not been hitherto detected in the corresponding formation of 

 the Niagara Limestone of North America, but species of the 

 same general type are abundant in the Devonian of Europe and 

 North America. 



Gemis CcENiTES, Eichwald, 1829. 



(Zool. Spec, t. i. p. 179.) 



Limaria, Steininger, Mem. Soc. G^ol. de France, t. i. p. 339, 1831. 



Gen. C//rt;r.— Corallum usually dendroid or frondescent, rarely 

 submassive. Corallites compressed, thin-walled in the centre of 



