548 



BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



It differs from Tub well u f/ibbosa in the absence of large zoarial gibbosities 

 around certain peristomies. 



On account of the size of the fragments this is an easily recognized fossil. 



Occurrence. Middle Jacksonian: Wilmington, North Carolina (common): 

 Eutaw Springs, South Carolina (very rare), 



Gotypes.C&t. No. 62605, U.S.N.M. 



TUBUCELLA GIBBOSA, new species. 



Plate 71, figs. 1-9. 



Description. The zoarium is free, bilamellar. diohotomously branched; the 

 fronds are wide and compressed. The zooecia are indistinct; the peristomiale is 



FIG. 161. Genus Titbiporella Levinsen, 1909. 



A-D. TuWporcllii mui/nirnstris MacGillivray. 1S82. A. Group of z-ooecia showing two peri- 

 stomial ovieells, X 23. B. View after removal of the basal surface. Two ovicells are seen and 

 the three zooecia show a distinct vestibular arch. X 23. C. A part of the surface of a zooecium, 

 X 55. D. A sagittal section through the zoarium. An ovicell is seen proximally and the two 

 zooecia show a vestibular arch at the beginning of the peristomial tube, X 17. (A-D after 

 Levinsen, 1909.) 



a little smaller than the frontal and they are separated from each other by a 

 small ascopore; the pores of the frontal are a little smaller than those of the peri- 

 stomiale. The peristomie is salient, little thickened: the peristomie is very long 

 and arched. Around the peristomie of certain zooecia the tubules are much de- 

 veloped, forming on the zoarium very prominent gibbosities. 



. fPeristome=0.20mm. 

 M casurement*. Zooecia ,. 



lZ.~=O.Somm. 



Affinities. The gibbosities which characterize this species are quite original. 

 The sections which we have prepared (figs. 8, 9) show that they result from the 

 extraordinary development of the tubules around certain peristomies. The zooecia 

 which bear them are without ovicells. In Tubucellaria nodosa it is. on the con- 



