CHAPTER n. 



Branch COELENTERATA. 



Class ANTHOZOA. 

 Order ZOANTHARIA. 



Sub-order ZOANTHARIA SCLERODERMATA. 



Family TURBINOLIDAE. 



Genus Fi^abellum Lesson. 



Flabellum mortoni Vaughan. 



Plate v., Figs. 1-4. 



1900. Flabellum mortoni Vaughan, Monog. U. S. G. S., vol. 

 39. P- 66, pi. 4, figs. 7-10. 



Description. — Corallum cuneiform, base small, edges and 

 faces converging towards it ; cross-section elliptical. Outer sur- 

 face O'f the corallum, when uninjured, covered by a smooth, 

 polished epitheca; costas absent or very slightly developed, when 

 present they are low, usually flatfish, and correspond to the in- 

 terseptal areas. The septa are thin in the upper part of the cor- 

 allum, in the lower portion they have undergone some secondary 

 thickening, but apparently not tO' sO' great an extent as in some 

 other species of the genus. The number of septa in an adult 

 calice about 70, the actual number cannot be made out because of 

 the condition of preservation of the specimens ; the free margins 

 oif the septa show transverse undulations and the septal faces are 

 granulate. (Adapted from Vaughan.) 



The dimensions of a nearly complete corallum are : greatest 

 diameter of the calice, 20.5 mm. ; lesser diameter of the calice, 

 12 mm. ; height of corallum, 21 mm. 



Remarks. — ^This species is one of the three common forms of 

 corals in the Manasquan marl, and may be easily distinguished 

 from its associates by reason of its somewhat flattened corallum 

 and its straight form. As it occurs in the marl beds the outer 



(267) 



