102 



BULLETIN 71, UNITED STATES NATIONAL MUSEUM. 



genus in rocks containing typical Fistuliporidse would suggest that 

 it represents a more permanent line of development, possibly giving 

 rise to such genera as the Devonian Pinacotrypa. 



Genotype. — FavositeUa interpuncta (Quenstedt) .^ Silurian (Wen- 

 lock shale) of England. 



FAVOSITELLA EXSERTA, new species. 

 Text fig. 36. 



Zoarium a lamellate expansion several centimeters in width and 

 usually about 4 mm. thick. Under surface, as usual in such forms 

 of growth, wrinkled and covered with an epithecal membrane. 



Fig. 36.— FAVOSITELLA EXSEKTA. O, EDGE VIEVT OF A ZOAEIUM, NATURAL SIZE, IMBEDDED IN THE KOCK; 6, 

 SUKFACE VIEW, X9, OF THE SECTIONED TYPE; C, TANGENTIAL SECTION, X20, EXHIBITING THE SMALL PROM- 

 INENT lunaeium; d, vertical section, X9, through portions of two layers; e, portion of the 



SAME, X20, ILLUSTRATING WALL STRUCTURE IN MORE DETAIL. KUCKERS SHALE (02), BAEON TOLL'S 



estate, Esthonia. 



Zocecial apertures rather large, direct, subpolygonal, and nearly 

 equal in size, 0.47 mm. in diameter, on the average with three to four 

 in 2 mm. Lunarium small, occupying less than one-seventh of the 

 zocecial wall, but so sharply elevated that it is a prominent surface 

 feature. Walls of both zooecia and mesopores quite thiQ. Meso- 



1 Favosites interpuncta Quenstedt, Petref. Deutsehl., Abth. 1, 1881, p. 10, pi. 143, fig. 9. 



