48 COELENTERATA—SPONGIAE CLASS I 
phery, and with finer radial canals leading from exterior to cloaca. Skeleton 
composed of irregular smooth-rayed tetraclons with root-like branching 

Fic. 54. 
Callopegma acaule, Zitt. Senonian; Ahlten, Hanover; a, Individual in 3/4 natural size; 6, Skeleton mag- 
nified 40/; ; c, Portion of periphery, 2/;; d, Same magnified 40/;, and showing anchors with furcate head-rays. 
extremities, disposed in rows parallel to the radial canals. Occurs (usually 
replaced by calcite) in the Ordovician of the Russian Baltic Sea Provinces, 

Fic. 55. 
i” 56 
Phymatella tuberosa, Quenst. sp. Quadratenkreide Bie. 66, 
(Upper Senonian); Linden, near Hanover. a, Sponge, Siphonia tulipa, Zitt. Greensand; Blackdown. 
I/y natural size; 6, Outer surface, 1/,; c, Skeletal A, Longitudinal section, natural size. B, Sponge with 
element, 50/; ; d, Spicules from stalk portion, 50/}. peduncle and root, 1/y natural size (after Sowerby), 
Ordovician of Illinois, and Silurian of Gottland. Also in erratic blocks on the 
plains of Northern Germany, usually chalcedonised. 
Archacoscyphia, Hinde. Cambrian. 
Callopegma, Zittel (Fig. 54). Bowl- or funnel-shaped, short-stemmed, thick- 
walled. External surface perforated by smaller, internal by larger canal-openings 
(ostia and postica). Skeleton composed of smooth-rayed tetraclons, the digitate 
extremities of which are inflated into balls. Dermal spicules in the form of 
anchors and rods. Upper Cretaceous. 
Phymatella, Zittel (Fig. 55). Upper Cretaceous. 

