EXPLANATION OF PLATES. 



Note. — The page numbers printed in the following matter refer to where the description is 

 iriven. Numbers (1, 2, 3, etc.,) refer to figures on the plate. The plates will be found be- 

 ginning on page 189. 



PLATE I. 

 Fusulina secalica, (p. 10.) 



1. Illustrates the different forms and sizes of these shells. 



1//. Longitudinal section of a specimen, showing the foramina in the inner 

 walls (/). 

 Amblyaiphonella j)ross(ri, (p. 14.) 



2. Longitudinal section much enlarged, showing pores in the walls and the 



thin gastral tissues. (After Clarke.) 



2b. Cross-section enlarged to show the structure. (After Clarke.) 



2c. Longitudinal section about natural size, showing the cloaca in the center 

 and the apertural walls. (After Clarke.) 



2d. Average-sized specimen. About natural size. (After Clarke.) 



'2' . Section of specimen as seen in matrix, from Topeka. Oblique longitu- 

 dinal section. 



2/'. Specimen of different form, and possibly different species. 

 Somphospongia multiformis, (p. 12.) 



• ;. Drawing to illustrate the thickness of the dermal layer. Magnified. 



7. Outline of larger specimen, showing mushroom form. One-half natural 

 size. 



s . Tracing of a section through the top of one of the sponges, showing the 

 arrangement of the canals, which are stippled. The unstippled 

 portion is the body of the sponge. One-half natural size. 



9. Semidiagrammatic section through the cloaca of a small individual, show- 



ing canals, which are stippled, and the semiconcretionary nature of 

 the outer part of it. 



10. Portion of the surface of a weathered specimen, showing what appears 



to be the body skeleton of the sponge. Magnified. 



PLATE II. 



Somphospongia multiformis, (p. 12.) 



1 to 5. Photographs showing the various forms of the smaller specimens, the 

 last showing the manner in which the tops of the sponges weather, 

 bringing out the canals. Less than natural size. 



Amblysiphonella prosseri, (p. 14.) 



6. Specimen showing aperture. About natural size. ( After Clarke.) 



( 175 , 



