PLATE XVIII. 



Fig. 

 1, 2, 2, a. Trigonia gihhosa, Sow. Variety with prominent nodose costae and wide 



ante-carinal space. Portland Oolite, Tisbury. Also 

 Plate XXI, fig. 1. (Page 84.) 



3. „ Bamoniana, De Lor. Variety with few large nodes upon the 



costae ; see also Plate XXI, figs. 2, 3, 4, 5. 

 Portland Limestone, Portland. (Page 88.) 



4. „ gihhosa. Variety with the costse small, partially plain or sub- 



tuberculated ; see also Plate XIX, fig. 2. Portland 

 Oolite, Tisbury. (Page 84.) 



5. 6. „ gibbosa. The typical form, longitudinal sulcations strongly 



defined. Portland Oolite, Tisbury. (Page 84.) 



t 



