DACTYLOPOKA. POLYPI. 485 



SECTION V. 



Polypiferous masses sub-stony, with crustaceous or frondescent 

 expansions ; cells small, short or not deep, sometimes in a se- 

 ries, sometimes without order, and in general disposed at the 

 surface of the expansions upon marine bodies. 



The animals of this section form their crustaceous expansions on marine bodies. 

 These expansions are simple, divided into lobes, or frondescent; but in all cases the 

 cells are small, sessile, rarely diffuse, generally in a series, or disposed like net- work 

 at the surface of the expansions, either on one of the faces or both. These cells are 

 short, subtubular, straight or oblique, sometimes contiguous, and disposed in regular 

 rows or diffuse, and in other cases isolated or separated. The terminal opening is 

 orbicular or triangular, with the margin often dentated or ciliated, or sometimes shut 

 by an opercular plate. The polypi, though aggregated, appear not to communi- 

 cate together. 



Gen. 89. DACTYLOPORA, Lam. 

 Stony, free, cylindrical, obtuse at one extremity, narrowed and 



pierced at the other ; exterior surface reticulated, the meshes 



rhomboidal ; pores very small. 

 D. cylindracea, Lam. (TReteporite, Bosc.) Lam. ii. 189. 



Gen. 40. OCELLARIA, Lam. 

 Stony, flattened as a membrane, variously bent, subinfundibuli- 



form, with the superficies arenaceous, furnished with pores 



on both surfaces ; pores disposed in quincunx order, with the 



centre elevated into a solid axis. 



Two species of this genus have been found fossil in France. 



Gen. 41. ALVEOLITES, Lam. 



Stony, forming incrustations or a free mass, in numerous con- 

 centric beds covering one another ; layers composed each of 

 a junction of tubular prismatic cells, short, contiguous, and 

 parallel, having the appearance of net-work at the exterior. 



A. incrustans, Lam. Covering marine bodies, such as Madrepores, 

 Gorgoniae, &c. the crust composed of a single layer of crowded 

 tubes, and forming a net- work of unequal pentagonal or hexago- 

 nal meshes. Lam. ii. 187- 



The other species of this genus are fossil. 



Gen. 42. RETEPORA, Lam. Mittepora, Lin. 

 Stony, porous interiorly, with thin, fragile, flattened expansions, 

 composed of branches sometimes free, generally anastomosed 

 like net-work ; cells of the polypi on one side only, at the up- 

 per or internal surface of the mass. 



R. reticulata. Lam. Flattened, ribbed, with irregular convolutions ; 

 internal surface warty and porous. Inhabits Mediterranean sea. 

 Ellis, Zoopk. 138. 



R. cellulosa, Lam. Flattened, submembranaceous, thin, reticulated, 

 turbinated, waved, base subtubular ; internal surface porous ; ex- 

 pansions pierced with elliptic cells. Inhabits Indian seas Ellis, 

 Zooph. pi. 26. fig. 2. 



