226 PALEONTOLOGY OF ILLINOIS. 



In the Rhizomorina the branchy or nodulose and irregularly 

 divided character of the spicules imparts a very distinctive ap- 

 pearance to them, yet when closely examined they are often 

 found to be comparable with those of the Anthaspidellidae. 

 Thus, in Jerieca, Zittel, a central rod and two principal divi- 

 sions at each end are frequently determinable. Lastly, in the 

 Megamorina, the large spicules from which the family takes 

 its name, occasionally also present points for comparison. 



In the canal system and outer form of the spongarium the 

 Anthaspidellidae agree best with the Rhizomorine sponges. Since 

 the skeleton elements also appear to resemble those of that 

 family more than they do those of the Tetracladina, Megamo- 

 rina and Anomocladina, it seems advisable to regard the new 

 family as the initial one of the Lithistidae, and as the best re- 

 presented section of the order in the palaeozoic rocks. 



HINDIA Duncan. 



Microspongia Miller and Dyer, Jour. Cin. Soc. Nat. Hist. vol. I. p. 37, 1878. 



The genus Hindia was originally described in 1879, by Duncan 

 as a calcareous sponge.* This view of the nature of the sponge 

 was in my estimation successfully combated by both Hindet 

 and Rauff$. These two observers, however, differ in the position 

 assigned by them to the genus, the former being inclined to re- 

 gard the genus as belonging to the Lithistid family Anomalo- 

 cladina, while the latter refers it without question to the Te- 

 tracladina. My own investigations lead me to accept Dr. Rauff's 

 conclusions as the most probable. In the main, my conclusions 

 respecting the minute structure of the sponge agree very closely 

 with those of both Rauff and Hinde, causing a detailed discus- 

 sion of the genus to be almost superfluous. Still, as the 

 points on which we differ will be brought out to better advan- 

 tage, and, particularly since no account of this important fossil 



* Ann. and Mag. Nat. Hist., ser. 5, vol. 4, p. 84. 



\ Catal. Foss. Sponges, Brit. Mus., p. 57, 1883; and Ann. Mag. Nat. Hist, for Jan. 1887. 



J "Ueber die Gattung Hindia Duncan;" Sitzungsb. der Niederrh. Gesell. zu Bonn; 

 Bitzung vom 10 Mar. 1886. 



