694 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



Measurements. 



Diameter of the peristome 0.16 mm. 



Distance between the peristomes 1.00 mm. 



Width of the branches 0.40 mm. 



Variations. This species is quite deceiving, as it closely simulates the abun- 

 dant and widespread Mecynoecia proboscidea Milne-Edwards, 1838 ; but it has only 

 a single celluliferous face. At Jackson, Mississippi, the specimens are more often 

 biserial: at the locality near Monroevlle, Alabama, they are triserial. The tubes 

 are rarely verticellate. 



Affinities. This species differs from Filisparsa laxata which has the same per- 

 istomial diameter, in its much smaller branches and in the number of its longitudi- 

 nal rows of tubes which are only two to three. 



Occurrence. Lower Jacksonian (Moodys marl) : Jackson, Mississippi (very 

 common). 



Middle Jacksonian: One-half mile southeast of Georgia Kaolin Company's 

 Mine, Twiggs County, Georgia (rare) ; 12 miles southeast of Marshallville, Georgia 

 (rare). 



Upper Jacksonian (Ocala limestone) : West bank Sepulga Kiver, Escambia 

 County, Alabama (very rare). 



Vicksburgian (Marianna limestone) : One mile north of Monroeville, Ala- 

 bama (very common). 



Cotypes.Czt. Nos. 65325, 65326, U.S.N.M. 



.FILISPARSA INGENS. new species. 



Plate 142, figs. 12-21. 



Description. The zoarium is formed of large dichotomous branches, pluri- 

 serial and compressed; the dorsal is ornamented with large, transverse wrinkles. 

 The tubes are distinct, very convex, arranged in very regular quincunx ; the peris- 

 tome is thick, orbicular, oblique. 



Diameter of the peristome 0.20-0.24 mm. 



Distance between the peristomes 0.80 mm. 



Measurements.- \ Separation of the peristomes 1.00-1.20 mm. 



Width of the branches 1.5-2.00 mm. 



Variations. The great number of specimens collected, and chiefly their large 

 size, has permitted us to make numerous sections for study. In transversal section 

 the great thickness of the frontal walls is to be observed. In longitudinal section 

 the tubes are short and issue on the dorsal at different heights; a short peristomie 

 is often developed. The ablation of the dorsal shows the habitual lozenge-shaped 

 areas formed by the projection of the tubes on the plane of the dorsal. The 

 tangential section of the frontal shows the usual tremocysts of the Cyclostomata. 

 The tangential section of the dorsal shows the same structure. 



