4 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES- 



fig. 5) in having the marginal serratures more angular, ami the cellules less 

 distinct ; while the stems appear to bifurcate less frequently. 



Locality and position. — South Branch of the Cheyenne River, near Black 

 Hills; in Fox Hills group, or formation No. 5 of the Upper Missouri Creta- 

 ceous, where it is associated with Avicula Nebrascana and Scaphites Manda- 



MP 71 SIS 



Genus MICROSTIZIA, Meek 



l'.hjm. — /ii.Kp6(, small ; otitic, puncture; in allusion to the numerous minute punctures of one side. 

 Type. — M. miUejnmctata, M. 



Microstizia millepunctata, M. 



Plate 28, figs. 2, a, b, c. 



The few fragments of this fossil yet found are so imperfect that no 

 attempt will be made here to give a formal diagnosis of the genus ; but, as it 

 seems not to agree in its generic characters with any of the described groups, 

 I have ventured to propose, provisionally, a new genus for its reception. As 

 nearly as can be determined from the imperfect specimens in the collection, 

 it appears to have consisted, when entire, of a reticulated, leaf-like corallum, 

 slightly flexed along the middle, but destitute of a distinct midrib. The 

 fenestrules on each side of this imaginary midrib are oval or subcircular, 

 and disposed in irregular oblique series ; while the middle portion is occu- 

 pied by two rows of more elongated, alternating fenestrules, arranged parallel 

 to the longer diameter of the fossil. Cross-fractures show the whole coral- 

 lum to be composed of an extremely thin, flattened, corneous central axis, 

 covered by a comparatively thick spongy tissue. 



The rays and dissepiments between the fenestrules are about equal in 

 breadth to the latter, and the only side yet seen is occupied by innumerable, 

 extremely minute, crowded punctures, or pores, entirely invisible to the un- 

 assisted eye, or even under a low magnifying power. As none of the speci- 

 mens in the collection show the opposite side, of the fossil, some doubts 

 remain in regard to the nature of the minute pores mentioned, which seem 

 entirely too small to be the cells occupied by the polyps. When better spec- 

 imens showing the other side can be examined, it will probably be found 

 occupied by the animal cells. 



It is only provisionally that this fossilyis placed here under the head of 

 the Alcyonaria, as it may be found even to belong to the Polyzoa. 



Locality and position. — Moreau River, Nebraska ; Fox Hills group of 

 the Upper Missouri Cretaceous series. 



