368 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



This genus is purely zoarial. The articulation is only an adaptation to some 

 special circumstances, particularly to life on large marine algae whose mobility 

 is very great. It is therefore not astonishing to note some apertures of different 

 form. On the other hand, the characters of adaptation can very well become fixed 

 in general descent and transform themselves into essential characters One must 

 not forget that the bryozoan individual is the zoarium issued directly from the 

 larva, and not the zooecium, which is only a bud of the aforesaid larva. 



In the present case our knowledge of the ovicells and the operculum is of little 

 importance. It is better, therefore, to admit the genus such as Tenison-Woods 

 has conceived it. 



The genus still exists in the waters off the coast of Florida, which is still 

 another proof in favor of the continuity of the faunas in the Gulf of Mexico. 



TETRAPLARIA TUBERCULATA. new species. 

 Plate 48, figs. 7-10. 



Description. The zoarium is articulated, the segments are composed of a 

 dozen zooecia placed back to back, disposed in four series, placed two by two at 

 right angles. The zooecia are little distinct, elongated, subcylindrical ; the frontal 

 is convex and formed of a tremocyst with small pores. The aperture is semilunar; 

 the proximal border is somewhat concave and bears a triangular rimule. On each 

 margin of the aperture there are two large symmetrical tubercles. 



. f/,3=0.12mm. 

 Measurements.- Zooecia , 1 



U3=0.11mm. 



Affinities. In the distinctly schizoporelloid form of its aperture this species 

 resembles very much Tetraplaria australis Tenison-Woods, 1878. 1 It differs 

 in its nonoblique aperture and the presence of two oral tubercles. 



Occurrence. Upper Jacksonian (Ocala limestone) : Chipola Eiver, east of 

 Marianna, Florida (rare). 



Cotypes.Cnt. No. 64070, U.S.N.M. 



TETRAPLARIA CAUDIFERA, new species. 



Plate 48, figs. 11-14 



Description. The zoarium is articulated ; the segments are formed of four longi- 

 tudinal rows of alternate zooecia, placed at right angles. The zooecia are distinct, 

 very elongated, narrowed in the back in the form of a tail; the frontal is convex 

 and formed of an incomplete tremocyst surrounding a sort of smooth plastron. 

 The aperture is elongated, elliptical, bearing two small, lateral denticles; there is 

 a small vestibular arch. On each side of the aperture there are two small, very 

 simple avicularia without denticle or pivot. 



I ha 0.19mm. . f Zs=1.3-1.5 mm. 



Measurements. Apertures \ 7 Zooecia . . 



I ia0.l?> mm. I /2=0.40 mm. 



1 It is to be noted that the figure given by Tenison-Woods 1878, resembles but little the figure of 

 MacGillivray, 1895. The first is smooth with a lepralioid aperture; the second is punctate with a schizo- 

 porelloid aperture. 



