SPONGES. 229 



This description would scarcely lead anyone to suspect that 

 the genus was founded upon a species which there is reason to 

 believe, is congeneric with Hindia sphaeroidalis. This belief is 

 based upon the fact that only one globular sponge is known to 

 me from the Cincinnati group, and that is unquestionably a 

 Hindia. I have also seen specimens of this species which had 

 been identified by Mr. Miller with his Microspongia gregaria. 



If the originals of Microspongia are indeed the same as Hindia 

 then we must decide whether the former name, which was pro- 

 posed a year or more before the latter, is or is not entitled to 

 recognition. If it is essential that a species or genus to be es- 

 tablished must be described so that it can be recognized, then 

 Microspongia cannot stand. There is nothing in the above 

 quoted description, save the assertions that it is a calcareous 

 sponge with (?) very minute needle shaped spicules, which would 

 not apply equally well to Astylospongia, Aulocopium and one 

 or two other palaeozoic subspherical free sponges; and, taking 

 for granted that the two names are really founded upon con- 

 generic species, the description is false in the very points ex- 

 cepted, since Hindia is an undoubted siliceous Lithistid sponge 

 with spicules of the Tetracladine type. Besides, the most im- 

 portant distinguishing features are not mentioned at all. Thus, 

 while there are many reasons for abandoning the name Micro- 

 spongia (always granting, of course, that the two names relate 

 to one and the same genus) I see none of sufficient importance 

 to justify its adoption at the expense of Hindia. 



Hindia is represented in Cambrian and Silurian strata by at 

 least three distinguishable varieties or species. The earliest, so 

 far as known, is from near the base of the Trenton group 

 (?Birdseye limestone) of northern Illinois. This is described in 

 this volume by Dr. Everett and the author as Hindia insequalis 

 its main distinctive character being an unusual inequality in 

 the size of the radial tubes. A nearly related smaller species 

 (H. parva Ulrich) occurs at numerous localities in the upper 

 or Galena division of the Trenton limestone, while a supposed 

 variety of the same is occasionally found in the upper beds of 

 the Cincinnati group at several localities in Illinois and Ohio. 

 The third species is the H. sphteroidalis. This species, which 



