PLATE 29. 
Page 
Fig. 1 a - o. Riiynchonella semiplicata. 224 
1 a, b, c. Young individuals which are nearly smooth, or with faint undulations towards the 
front. 
1 d, e. A small individual having the front extremely plicated. 
1 f- n. Illustrations of the prevailing forms, variety of plications, etc. 
1 o. Enlargement of the surface, showing the concentric and longitudinal striae. 
Fig. 2a- i, & 3. Riiynchonella asqui valvis.* 224 
2 a, b, c. Young individuals of this species. 
2 d. e,f & h. Dorsal, ventral, profile, and front views of a larger individual. 
2 i. Enlargement of th6 concentric striae. 
3 a. b, c. An individual having a shorter and more rotund form, with a faintly marked sinus 
in front. This is probably a distinct species. 
Fig. 4 a - o. Riiynchonella mutabilis. 225 
4 a, b, c. Young shells having a more elongate form than the prevailing types. 
4 d - fc, and p. The shorter form of this shell in the smaller individuals. 
4 l-o. The ovoid forms of this species. 
* This species is probably not a true Rhynchoneli,a : its surface-characters and form approach to Renssel^ria, 
while in other respects it resembles RnYNcnospiRA. 
