52 



COELENTERATA SPOXGIAE 



CLASS I 



Doryrhrma dichotoma, Roem. s 



FIG. 04. 



Upper Cretaceous, 



a, Sponge, natural size ; 



. sp. , , , 



Dermal layer, -'/! : c, Bundle of skeletal elements, !/! ; d, Skeletal element and 

 several dermal spicules with furcate, anchor-shaped head-rays, 3 <>/j. 



Saccospongia, Rauff. Silurian. Megalithisia, Zitt. Upper Jurassic ; Nattheim. 



Donjderma, Zitt. (Fig. 64). Sponge-body cylindrical, simple or branching, 



pyriform or compressed, with a number of larger canals running parallel 



with the body axis, and numerous smaller radial canals. Skeletal elements 



large, bent, and 

 divided into two 

 or more simple 

 branches. Dermal 

 spicules in the 

 form of three- 

 fluked anchors. 

 Upper Cretace- 

 ous ; Northern 

 Germany, Eng- 

 land, and France. 

 According to 

 Hinde, also Car- 

 boniferous. 



C art er ella, 

 Zitt. Cretaceous. 

 Isorhaphinia, 

 Zitt. Sub -cylin- 

 drical, pedunculate, with wide cloaca reaching nearly to the base. Skeletal 

 elements large, slightly bent, rod-shaped, inflated at the ends, rarely dichoto- 

 mously branching. They are associated in bundles, and so interlocked at their 

 extremities as to form an open meshwork. Cretaceous. /. texta, Roemer sp. 



Sub-Order E. RHIZOMOEINA. Zittel 



Skeletal elements small, composed of four or of three principal rays, or simple and 

 irregular, with numerous projecting spines or tubercles ; axial canal simple or branching. 

 Dermal spicules monaxons, tetraxons, or similar to those of the skeleton. Chiefly 

 Jurassic, Cretaceous, and Recent. 



1 Nipterella, Hinde. Cambrian. 



Cnemidiastrum, Zitt. (Cnemidium, p. p. Goldf.), (Fig. 65). Turbinate or bowl- 

 shaped, with deep cloaca. Walls thick, perforated by numerous radial canals 

 disposed in tiers one over another, thus forming vertical fissures which often 

 divide toward the exterior. Skeletal elements irregularly branching, entirely 

 beset with blunt, spiny processes. Abundant in the Upper Jurassic Spongiten- 

 kalk of South Germany, the skeletons being almost invariably replaced by 

 calcite. C. rimulosum, Goldf. According to Hinde also present in the 

 Carboniferous Limestone of Ireland. 



1 1 i/alotragos, Zitt. Bowl-, plate-, or funnel-shaped, with short peduncle. 

 Depression in summit perforated by the ostia of numerous short canals. Ex- 

 ternal surface finely perforate, or covered by a smooth or wrinkled dermal layer. 

 Skeletal elements irregular, with numerous branches beset with points, but with few 

 spines. Very abundant in Upper Jurassic Spongitenkalk. H. patella, Goldf. sp. 



Platychonia, Zitt. Leaf- or ear-shaped, irregularly undulating, covered on 

 both surfaces with fine pores. Skeletal elements resembling those of Hyalo- 

 tragos. Upper Jurassic. P. vagans, Quenst. sp. 



