422 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



discovery. The avicularium develops on a lateral areola slipping under the frontal 

 in the form of a triangle and developed longitudinally at the middle of this frontal 

 (pi. 54, fig. 17). 



HOUZEAUINA ORNATA, new species. 



Plnte 54. figs. 12-17. 



Description. The zoarium is an Eschara the fronds of which reach frequently 

 more than a centimeter. The zooecia are quite elongated, distinct, rectangular, 

 separated by a salient thread; the frontal is flat, smooth, ornamented laterally with 

 numerous areolae often very large. The aperture is subcircular. The ovicell is 

 buried in the distal zooecia, globular and salient and has a very fragile olocystal 

 frontal. The aviciilarium is median, somewhat salient, triangular, the beak turned 

 toward the bottom and provided with a pivot. 



[Aa=0.1Smm. Aperture of \ka=0.10 mm. 



| 7fl=(m _ 16 ovicelled zooecia |?a=0.14 mm. 



. I 2=0.80-0.90 mm. 

 Zooecia 7 nn . n 



Us=0.24-0.30 mm. 



Variations. The dimensions of the aperture which we mention are the maxi- 

 mum; most of the time they vary around 0.12-0.14 mm. by 0.12mm. The aper- 

 ture of the ovicelled zooecia is transverse: nevertheless in looking at the base of the 

 locella the zooecial aperture is perfectly visible with a greater height (0.12-0.18 mm. 

 and not 0.10 mm.). If this aperture were closed by an ordinary operculum it would 

 not be able to open exteriorly to allow the passage of the tentacles. It is this 

 which makes us suppose that the ovicelled zooecia have a special operculum. The 

 areolae are small (fig. 14) or large (fig. 13). 



The active formation of the pleurocyst gives to the zooecia a remarkable orna- 

 mentation (fig. 16) impossible to describe. In the interior (fig. 17) we see a thick 

 olocyst perforated laterally by some very small areolae, and the triangular cavity 

 which is the lodging of the aviciilarium by which the mesenchymatous elements 

 pass through one of the lateral areola. When the aviciilarium does not exist (fig. 

 13) the areolae are larger. 



Affinities. This is the American representative of TJouzcauina parallela 

 Reuss. 1869. It differs from it in its orbicular orifice (and not semilunar) with- 

 out a straight proximal border. 



It differs from Houseauina < allota in its smaller oral dimensions (Za=0.14, 

 and not 0.18 mm.) in its larger areolae and the much larger frontal callosity. 



Occurrence. Middle Jacksonian : Rich Hill. Crawford County, Georgia (com- 

 mon) ; Balclock, Barnwell County, South Carolina (very common) ; 3-i miles north 

 of Grovania, Georgia (rare) ; 3| miles south of Perry. Georgia (rare) ; 18 miles 

 west of Wrightsville. Georgia (common); Eutaw Springs, South Carolina (rare). 



Cotypes.Cat. No. 64111, U.S.N.M. 



