■Contributions to Invertebrate Palaeontology. 611 



GoNiopHOKA D0BIA Hall. Page 514. 



Fig. 24. View of a right valve, natural size. 



Fig. 25. Cardinal view of the two valves in outline. 



Fig. 26. Enlargement of a similar valve. 



Leperditia alta Conrad. Page 517. 



Fig. 27. The right valve of a specimen enlarged showing slight indications 

 of the ocular tubercle. 



Leperditia angulifera Whitf. Page 518. 



Figs. 28 and 29. Views of a right and a left valve showing a very slight 



variation in form. 

 Fig. 30. Outline profile of tlie valves united. . 



Eurypterus Eriensis Whitf. Page 515. 



Fig. 31. View of a head-plate showing the rounded front, the small ocular 



tubercles, and small single facets between them. 

 Fig. 32. View of the dorsal surface of the thorax lacking the terminal spine. 



PLATE YI. 



Stylastrea Anna Whitf. Page 520. 



Fig. 1. View of the upper surface of a specimen showing the centre of the 



cells occupied by the transverse tabulae. 

 Fig. 2. Longitudinal section showing the external surface of the cell-walls 



striated by the rays. 

 Fig. 3. Enlarged transverse section of a single cell to show the vertical inter- 

 radial ridges extending from the sides of the rays. The central 



portion also shows the tabular plate. 

 Fig. 4. Vertical section of a part of a large mass, showing the tabulae and also 



the side of the vertical rays with vertical ridges and intermediate 



cystose structure. 

 Fig. 5. Transverse section of several cells, natural size, and showing the 



transverse tabulae. 



Rhynchonella raricosta Whitf. Page 522. 

 Fig. 6. View of the ventral valve of the specimen described. 



Streptorhynchus flabellum Whitf. Page 521. 

 Fig. 7. View of a ventral valve. 

 Fig. 8. View of the dorsal valve. 

 Fig. 9. Cardinal view of the specimen fig. 7, enlarged to two diameters. 



Receptaculites Devonicus Whitf. Page 519. 

 Fig. 10. View of the specimen described. 



