3QO MAY M. JAKVIS. 



shape and arrangement ; these seem to indicate an erosion of the 

 ridges and the papillae. In some, again, the ridges have worn 

 away, leaving only the papillae, but the arrangement of these is 

 as in the other cases. At the summit of each papilla, or at the 

 center of each depressed area, is a minute foramen penetrating 

 the wall of the test. 



Fig. 7 shows the structure in ideal cross section. The whole 

 interior is filled completely with foreign, calcareous substance, 

 containing fragments of sponge spicules. 



In no one specimen is the sculpturation preserved over the 

 entire fossil, but a comparison of the different ones shows that 

 the test in life, except just around the foramen, must have been 

 so sculptured. The radial canals around the foramen are usually 

 continued upwards as rows of minute depressions. Possibly 

 such radial canals were not present in life, but produced by ero- 

 sion of the exterior. 



Measurements. The largest specimens have a diameter of 

 25 x 31 mm. ; smaller ones from 9 to 18 mm. The large basal 

 foramen measures from 4 to 7 mm. across. 



These fossils present few good characteristics to enable one to 

 decide what their nature was. But there is no resemblance, as 

 Cragin had supposed, to Bryozoa, for even in a colonial ecto- 

 proctous Bryozoan the cysts of the separate individuals are more 

 or less cylindrical, and there is no sign at all of any such 

 structures. Evidently the structure is that of a very thin shell 

 or test, without prolongations into the interior, with a large 

 opening at one end and rows of numerous minute foramina else- 

 where upon the surface. This general appearance suggests 

 that it is a gigantic monothalamnian Foraminifer that in the 

 course of fossilizatioli has become infiltrated so as to be quite 

 solid. Were it Bryozoan there should be present traces of skele- 

 tal parts within the test. 



