M. K. A. Zittel 071 Fossil Lit/ti'stiJce. 481 



rally bj a short stalk. Wall thick ; margin rounded off. 

 Both surfaces with anastomosing furrows, which are either 

 quite irregular or show an indistinct radial arrangement, 

 sometimes forming indistinct stellate figures. From these 

 furrows canals run straight or obliquely into the wall. The 

 four arms of the skeletal corpuscles are divided each into two 

 or more rather long warty branches, the ends of which are 

 again repeatedly notched. Some of the corpuscles are pretty 

 uniformly tubercular ; others have the arms near the centre 

 smooth or with a few tubercles. On the surface there is a 

 complete coat of smooth large and small corpuscles of peculiar 

 structure. The larger have a spiniform shaft, from the 

 thickened end of which issue three broad horizontal arms, 

 divided into two, three, or more deeply cleft lobes ; in the 

 centre of each corpuscle is a quadriradiate axial cross. These 

 lobate disks are bound together by a network of small, smooth- 

 armed, irregular siliceous bodies. 



The only known species of this genus is described by 

 Rdmer (Spong. p. 51, xvii. 8) as Citpulosjyoiigia rimosa. 

 The numerous specimens from the Upper Cretaceous of Ahl- 

 ten, however, will have to be divided into two or three species. 

 Individual specimens attain a breadth of 130-150 millims., 

 with walls 30 millims. thick. 



Plinthosella, Zitt. 



?Achilleum and Amorphospongia p. p., Rom. 



Sponge globular or irregularly nodular, free or attached by 

 a short stalk, without a central cavity. Surface with irregu- 

 larly distributed furrows and scattered apertures, connected 

 with more or less deep curved canals. The whole sponge- 

 body consists of a loose coarse texture of quadriradiate cor- 

 puscles of considerable size. These corpuscles are covered 

 with rounded gnarled warts ; and the arms are but slightly, if 

 at all, branched. Surface covered with a thick layer of im- 

 bricated siliceous scaly plates of irregular form — roundish, 

 polygonal or elongated, lobate or with long processes. Their 

 surface is roughened. Only in the Cretaceous. 



1. Plinthosella squamosa^ Zitt. 



?Achilleum deforme, Rom. Kr. p. 2. 



Globular bodies 5-25 millims. in diameter. Skeleton 

 beneath the scaly layer traversed by furrows and furnished 

 with rounded ostia. Quadratus-c\i9\^ of Ahlten and Linden in 

 Hanover. 



Ann. & Mag. N. Hist. Ser.-5. Vol. ii. 32 



