154 



BULLETIN 77, UNITED STATES NATIONAL MUSEUM. 



SCEPTROPORA FRANCISCA, new species. 

 Text fig. 75. 



Zoarium of club-shaped segments bluntly pointed at the proximal 

 end for articulation with the preceding segment. The average indi- 

 vidual segment is 4 mm. in length and expands slowly from the basal 

 portion to the distal end which is abruptly rounded and about 2 mm. 

 in diameter. All portions of the segments are cell bearing excepting 

 the extreme base and top, where articulation occurred. The aper- 

 tures are angular and arranged somewhat irregularly in rows between 

 longitudinal crests formed by the union and greater development of 

 the walls alons; such lines. Seven zooecia occur in 2 mm. In some 



4orf 



Fig. 75.— Scepteopora fkancisca. a, group of three segments, natural size; b, the largest seg- 

 ment, X9; C, BASAL PORTION OF THE SAME SPECIMEN, X20; d, TANGENTIAL SECTION, X20; 6 AND /, VER- 

 TICAL AND TRANSVERSE SECTIONS, X20, SHOV/ING GROWTH OF ZOCECIA FROM CEl'TTRAL AXIS. WASSALEM- 

 BEDS (D3), UXNORM, ESTHONIA. 



specimens certain apertures are small and irregularly angular, giving 

 the appearance of mesopores. These, however, are probably only 

 young zocecia, for thin sections show no trace of ordinary mesopores. 



Aside from the different shape of the segment, vertical sections 

 show Httle difference from those of the genotype. The zooecia arise 

 from a distinct central axis marked by a definite line, and proceed to 

 the surface in a gentle curve, the walls as usual becoming thickened 

 in the mature zone. Transverse sections of the two species are iden- 

 tical. In tangential sections the zooecia are noted to have rather a 

 regular polygonal outline and arrangement in longitudinal rows. 



The small, neat segments of S.francisca are too distinct from other 

 species of the genus to require comparison. The specific name is in 



