Mr. A. E. Verrill on the Classification of Polyps. 191 



defined, the others nodulated and less distinct. The valves 

 are covered, between the ridges, with rounded tubercles. In 

 young specimens the longitudinal ridges are sharper, the 

 surface-tubercles are sharp and spinous, and the elevated an- 

 terior border is absent or indistinct. The young state of this 

 species is represented in figs. 12-15. Length (of the adult) 

 -jLrd of an inch. 



The above description applies to well-marked specimens ; and 

 much latitude must be allowed as to the amount of spinous and 

 tubercular development, especially with reference to the squa- 

 mous spines and lamina of the posterior extremity. 



EXPLANATION OF PLATE IX. 



Fig. 1. Cy there carinata (Brady), left valve, X 50. 



Fig. 2. The same, seen from above, X 50. 



Fig. 3. The same, seen from below, X 50. 



Fig. 4. The same, end view, X 50. 



Fig. 5. Cy there arborescens (Brady), perfect carapace, X 40. 



Fig. 6. The same, seen from above, X 40. 



Fig. 7. The same, seen from below, X 40. 



Fig. 8. The same, end view, x 40. 



Fig. 9. Cytheridea punctillata (Brady), left valve. X 40. 



Fig. 10. The same, seen from above, X 40. 



Fig. II. The same, end view, X 40. 



Fig. 12. Cythere aspera (Brady), right valve (young), X 40. 



Fig. 13. The same, seen from above, X 40. 



Fig. 14. The same, seen from below, x 40. 



Fig. 1 5. The same, end view, X 40. 



Fig. 16. The same, adult right valve, X 40. 



Fig. 17. The same, seen from above, x 40. 



Fig. 18. The same, seen from below, x 40. 



Fig. 19. The same, end view, X 40. 



XXVI. Classification of Polyps. {Extract condensed from a Syn- 

 opsis of the Pohjpi of the North Pacific Exploring Expedition 

 under Captains Ringgold and Rodgers, U.S.N) By A. E. 

 Verrill*. 

 The report upon the collection made by Dr. William Stimpson, 

 naturalist to the expedition, having been much delayed, the 

 following tabular view of the classification adopted is here pre- 

 sented, with the hope that, if imperfect like every other, it may 

 nevertheless afford some aid in illustrating the natural affinities 

 of these humble forms. 



Although, in a communication read before a zoological club 

 at Cambridge, January 1862, I attempted to demonstrate the 



* From the * Proceedings of the Essex Institute,' U. S., for 1865. 



