Cretnc'ons and Tertiarij Cirr'} pedes. 



201 



but when we turn to Pollicipes mitella we see that it has 

 a single lower whorl of valves including a subrostrura and 

 subcaiina, and with a short peduncle, which is sometimes 

 even considerably shorter than the capitulum. 



Fijr. 2. 



sr 



Fig. 4. 



X 



Fig. 5. 



Fig. 2. — Pollicipes mitella, Linnteus. Living : Philippines, Cliina, &c. 



(After Darwin.) 

 Fig. 3. — Catophragmus polymerus, Darwin. Living: Australian Coast. 



(After Darwin.) 

 Fig. 4. — Pycnolepas rigidus, J. de C. Sowerby, sp. Albian and Ceno- 



manian, Europe. Restoration. 

 Fig. 5. — Ih-achglepas naissanti, H(5bert, sp. Upper Senonian, Europe. 



Restoration. 



c, carina; c.l., carina! latus; i.s., imbricating plates; I., upper latus ; 

 r., rostrum; r./., rostral latus; s., scutum; s.c, subcarina; s.r., sub- 

 rostrum ; t., tergum. 



The blocks for figs. 2, 3, and 5 were kindly lent by the editor of the 

 ' Geological Magazine.' 



While it may be supposed that the pedunculate Pycnolepas 

 was the ancestral stock which gave rise to the sessile 



