Maryland Geological Survey 263 



the family, and, iu particular, Fistulipora. The elevation of the inter- 

 apertural space to form the so-called vestibular area is by no means a 

 constant character even in the same individual of F. constricta. Then as 

 to the oval interzocecial cells, they are distinguishable only where the sur- 

 face has been somewhat worn ; the perfect condition, which is clearly in- 

 dicated on some of the specimens, showing that they are only remnants 

 of an extra superficial, cellulose tissue formed by the abundant develop- 

 ment and lateral confluence of rod-like prolongations of the walls of the 

 vesicles through the dense outer layer that occurs in all Fistuliporidas. 

 Possibly these oval outlined remnants in F. constricta lodged a distinct 

 type of zooid, since very similar cells occur in other species in which the 

 superficial cellulose tissue is very incompletely developed. 



The writers conception of the essential characters of the generic group 

 for which the name Fistuliporella is adopted, is based principally upon the 

 either isolated and spine-like or laterally confluent prolongations of the 

 interstitial walls, which in the former case appear as mere granulations or 

 spines upon the surface, and in the latter form a wholly superflcial, cellu- 

 lose tissue. In tangential sections, these structures are seen to be de- 

 veloped only in the outer parts of the zoarium, beginning as swellings of 

 the walls of the vesicles just before the development of the dense tissue 

 characteristic of the mature region. In this dense tissue through which 

 these structures pass, they appear either as isolated dots or as laterally 

 united rows of such dots, their position in all cases corresponding to that 

 of the wall of the last interstitial vesicle. Used in this sense, the genus 

 will include, besides Simpson's type, Lichenalia cornuta and. L. ramosa 

 Hall and Simpson, Fistulipora eriensis, sjtinulifera, and utriculus Rom- 

 inger, and F. interaspera Hall and Simpson, from the Hamilton, the 

 species next described and several undescribed forms from the Niagaran 

 strata. 



Fistuliporella cumulata n. sp. 

 Plate XLI, Figs. 1-5 



Description. — Zoarium forming by the superposition of successive layers 

 of growth, rounded or irregular masses 20 to 30 mm. in diameter; indi- 

 vidual lavers 1 to 3 mm. in thickness. Surface even, but exliibiting 



