92 SILICEOUS SPONGES. 



is correct, Astylospongia prcemorsa can hardly be regarded as a hexactinellid sponge, 

 but shows a near relationship in its minute structure to the Lithistid genera Cylin- 

 drophyma and Melonella. 



As, however, further observations are necessary to establish the true character of 

 the spicular structure of Astylospongia, I prefer in the meantime not to remove the 

 genus from the position assigned to it by Prof. Zittel. 



ASTTLOSPONGIA PE.EMORSA, GoldflCSS, Sp. 



1833. Siphonia prcemorsa, Goldf. Petref. 1 Th. p. 17, t. 6. £. 9. 



1833. Siphonia excavata, Goldf. Petref. 1 Th. p. \7, t. 6. f. 8. 



1860. Astylospongia prcemorsa, F. Roemer, Silur. Fauna d. west. Tenn. p. 8, t. 1. £. 1. 



1877. Astylospongia prcemorsa, Zitt. Studien, I Ab. p. 45 ; id. Neues Jahrbuch, p. 353, t. 2. 

 f. 1; id. Handbucb der Pal. p. 172, £. 88. 



1878. Astylospongia prcemorsa, Martin, Archiv des Vereins d. F. d. N. Mecklenburg, p. 1, 1. 1. 

 1878. Siphonia prcemorsa, Quenst. Petref. Bd. 5, p. 551, t. 141. f. 1-3. 



Distribution. Silurian (Niagara group) : Waldron, Indiana ; Bath Springs, Perry 

 County, Tennessee. 



ASTTLOSPOXGIA STELLATIM-SULCATA, Rcemer. 



1848. Spongia stellatim-sulcata, F. Roemer, Leonh. u. Bronn's Jahrbuch, p. 686, t. 9. f. 5. 

 1860. Astylospongia stellatim-sulcata, F. Roemer, Silur. Fauna d. west. Tenn. p. 11, t. 1. 

 f. 2, 2 a, 2 6. 



Distribution. Silurian (Niagara group) : West Teimessee. 



AsTTLOSPOXGiA iNCiso-LOBATA, Ecemer. 



1848. Spongia inciso-lobata, F. Roemer, Leonh. u. Bronn's Jahrb. p. 685. 



1860. Astylospongia inciso-lobata, F. Roemer, Silur. Fauna d. west. Tenn. p. 11, 1. 1. f. 3, 3a. 



Distribution. Silurian (Niagara group) : Bath Springs, Perry County, Tennessee. 



ASTTLOSPONGU IMBRICATO-AETICULATA, RoemeT. 



1848. Siphonia imbricato-articulata, Rcemer, Leonh. u. Bronn's Jahrb. p. 685, t. 9. f. 3. 

 1860. Astylospongia imbricato-articulata, Roemer, SUur. Fauna d. westl. Tenn. p. 12, t. 1. 

 f. 5, 5 b. 



Distribution. Silurian (Niagara group) : West Tennessee. 



Asttlospoxgia'? EffiiiEPj, Einde, n. sp. (Plate XXIII. figs. 1, 1 «, 1 b.) 



A fragmentary specimen, ha^'ing the spicular structure of the genus, but the 

 portion preserved is insufficient to determine the complete form and canal-structure. 

 The fragment is of a conical form, with open sinuous channels 1'75 mm. wide 



