PLATE VII. 



LAOTIRA CAMBRIA (p. 32). 



Fig. 1. View of the exumbrella of an individual in which there is a departure from the radial 

 arrangement of the lobes shown in the specimen illustrated on Pis. V and VI, the short 

 lobes da being an added feature. They correspond to the subumbrella lobes aa, fig. la. 



Fig. la. Subumbrella side of fig. 1. In this it will be noticed that the arrangement of the lobes 

 near the center gives a slightly transverse central portion. 



Fig. 2. View of an exumbrella in which the lobes have been slightly upturned by lateral com- 

 pression. 



Fig. 2a. Subumbrella side of fig. 1. The lobes are narrow and do not meet around a center, the 

 tendency to a transverse arrangement being greater than in fig. la. 



Fig. 3. Subumbrella surface of a small specimen in which the lobes are turned in toward the 

 center. 



Fig. 4. Exumbrella view of a rounded, somewhat melon-shaped specimen. 



Fig. 4a. Subumbrella surface of fig. 4. in which the lobes are turned inward, very much as in fig. 3. 



Fig. 5. View of an individual illustrating the mode of occurrence of a large number of specimens. 

 They appear to be the upper portion of a flattened concretion, the siliceous matter hav- 

 ing been deposited between the lobes and over the subumbrella surface so as to conceal 

 it. and often over much of the exumbrella surface. 



Fig. 6. Subumbrella view of a specimen in which the lobes are very strongly defined. It may be 

 compared with fig. la. 



Fig. 7. A specimen preserved in the same manner as fig. 5, but which has been worn by weather- 

 ing so as to expose the radiating canals of the exumbrella lobes. 



Fig. 8. A specimen in which it is difficult to decide whether it is the exumbrella or subumbrella 

 surface that is preserved. It is apparently the exumbrella. 



118 



