[DrfWSOK] FOSSIL SPONGES AND >THER ORGANIC REMAINS 

 6. — ProtosPONQIA CYATHIKORMIH, DuWSOU. 



(Figs. 15 and IG. PI. II., Figs. 7 and 8.) 



107 



Fio. lo.—Protoapongia vi/alhi- 

 formis. Restored. 



Ft(i. 10.— Protoapongia cyathifonnia . Primary, 

 .secondarj' and tertiary cruciform spicules, x 5. 



General form inverted conical. "When mature about 3 cm. wide at 

 top and 5 cm. long, without the anchoring-spicules, which are sometimes 

 very long. Top truncate as if with a wide osculum, with defensive 

 spicules on its margin. Primary spicules cruciform, with long rays, in 

 some 2 to 3 mm. in length, placed diagonally, loosely attached or free, 

 but forming large rhombic meshes ; secondary and tertiary- spicules 

 numerous and delicate, with slender arms. Root spicules simple, some- 

 times very long, five or more visible in the most perfect specimens, and 

 passing up to the middle of the body. Indications of many interior 

 minute flesh spicules, often constituting a pyritized maas, obscuring the 

 meshes. 



The oblique character of the transvei-se spicules deserves notice, but 

 this may be the result of compression, though I think it more likely that 

 it is an original feature. 



This species is well characterized b}- its form, and by its multitudes 

 of very minute cruciform spicules. These, and the fact of the sponge 

 being often represented by a dense, pyritous mass, indicate a thicker and 

 more fleshy body-wall than in some other species. 



