1871.] DTJXCAN PERSISTENCE OF CARYOPHYLLIA CYLINDKACEA. 435 



The following diagnosis of the species was published by MM. 

 Milne-Edwards and Jules Haime in their last work, the ' Histoire 

 Naturelle des Coralliaires,' vol. ii. p. 19 : — 



" The corallum is elongate and subcylindrical, straight or slightly- 

 curved ; the lower two- thirds of the wall are smooth and glistening, 

 but in the upper third there are small subequal and very slightly 

 prominent costae. The calice is subcircular. The columella is fasci- 

 culate, and is composed of a small number of delicate ' tigelles.' 

 There are four cycles of se^ita ; but in the halves of three systems 

 the septa of the fourth and fifth orders are absent. The septa are 

 thin, but externally they are slightly thickened. The pali are narrow 

 and thick." 



An examination of a series of forms referable to this species 

 proves the general correctness of this diagnosis ; but still it is not 

 sufficiently exact. Some rather important structural details, which 

 were noticed by these careful naturalists in their ' Monograph of the 

 British Fossil Corals' (Pal. Soc), are not contained in the above 

 diagnosis, and yet they certainly should have been. For instance, 

 the spreading base of the corallum narrowing rapidly into a more 

 or less cylindrical stem, and the occasional perfection of the 

 fourth cycle in all the six systems, are details which cannot be 

 overlooked. 



It is quite true that corals with broad bases may become detached 

 above the base, and that they then possess a pedunculate appear- 

 ance ; but the presence of a broad base is a positive structural 

 peculiarity. 



The occasional perfection of the fourth cycle has not been ob- 

 served by me ; but it is consistent with the variability of the septal 

 arrangement in other species in which irregular septal systems 

 prevail. 



The distinctive structural peculiarities of CaryophyUia cylindracea 

 are the general shape, the condition of the wall, the development of 

 the costae, and the septal arrangement. 



CaryopTiyllice with four cycles of septa complete in each of six 

 systems, and with the incomplete arrangement noticed in the spe- 

 cies under consideration, were formerly supposed to be extinct, and 

 to have been restricted to the Cretaceous and Tertiary periods. The 

 following are species with four perfect cycles : — 



Cari/o]phyllia BowerhanM, Ed. & H., found in the Gault. 



„ Debeyana, Ed. & H., from the Chalk of Aix-la-Chapelle, 



„ Bredai, Ed. & H., from the Maestriclit Chalk. 



„ cylindrica, Ed. & H.. from the Maestricht Chalk. 



„ Haimei, Ed. & H., from the Maestricht Chalk. 



„ Sismondai, Ed. & H., Turin Miocene, Sicily. 



„ arcuata, Ed. & H., Older and Newer Pliocene. 



Seguenza has, moreover, described many species with the four 

 cycles fully developed from the Older Pliocene of Sicily. 



A species with the same septal arrangement has been found m 

 the volcanic sands of Guadaloupe. 



2h2 



