PAPERS ON GEOLOGY AND GEOGRAPHY 201 



Lower Davenport Beds. 

 2. Limestone, white to dark gray, fine grained, in layers '2 to 3^ 

 feet thick, with few fossils, in places finely laminated, usually 

 much fractured and brecciated, with fragments 1 to 24 inches in 

 diameter. Exposed in the Cady quarries in East Moline. in the 

 the Government Island, in the south bank of Mississippi River 

 in Rock Island, and forms the bed rock in Rock River valley 

 between Milan and Sears — fossils few or none 55 



OTIS LIMESTONE. 



1. Limestone, light to dark gray, fine grained, not brecciated. in 

 irregular layers, containing spherical concretions of chalcedonic 

 qnartz, and numerous shells of Martinia subumbona. Exposed on 

 the east side of Campbell's Island above Moline. and in the east 

 bank of Mississippi River opposite the island 20 



ZAPHRENTIS PUTILLA N. SP. 

 Plate I. Figures 3 and 4. 

 Description: — Corallum simple, conical straight or slightly curved, sub-cir- 

 cular in cross-section, diameter increasing gently and at a rather uniform rate 

 from the apex. Surface marked by rather distinct septal furrows, and by oc- 

 casional transverse wrinkles, or ridges and depressions, which are usually 

 small: rim of calyx thin, very little oblique; the calyx moderately deep con- 

 tracted below, with a rather large fossula; major septa commonly about 24, 

 ranging from 20 to 30. depending on the size or age of the corallite. their 

 inner extremities nearly or quite reaching the center; alternating with the 

 major septa are an equal number of low, secondary, septa which are some- 

 times scarcely more than septal ridges. 



The dimensions of two individuals are: Length 20 to 30 mm., diameter of 

 cahTC 10 to 14 mm. 



This species diflfers from most species of Zaphrentis in its small size, the 

 slight, if any. curvature, and the very gradually expanding corallum. It lacks 

 the pseudecolumella or vesiculose central area of Stereolasma rectum Hall, 

 and Streptelasma strictum Hall, with which it most nearly corresponds in 

 size. It is distinguished from Zaphrentis calcareforme in that the shorter septa 

 do not join the longer, and the latter are not united Adth the wall of the fossula. 



Horizon and Locality: — Common in the Cedar VaUey limestone along Mill 

 Creek, near Milan, where it occurs a few feet below the Acervularia coral reef. 



DIPLOPHYLLUM? MAJOR N. SP. 

 Plate I, Figures 1 and 2. 

 Description: — Corallum compound, in rather dense masses 1 to 2 feet in 

 diameter. The corallites are cylindrical, more or less parallel, nearly con- 

 tiguous or separated from one another by a distance less than the width of 

 the corallites. not connected by prolongations of the epitheca. circular in cross 

 section, varv'ing from 8 to 12 mm. in diameter; marked on the surface by 

 indistinct longitudinal lines resem.bling septal ridges, and also by fine trans- 

 verse lines, and rather strong annulations and constrictions. The calyx is 

 moderately deep, septa about 40. more or less undulating, half of them longer 

 than the others and joined together irregularly at the center, or uniting near 

 the center, to form an inner ring or wall surrounding a small central area. 

 The alternate or secondary septa are shorter than the primary ones, and ex- 

 tend slightly more than half the distance from the periphery' to the center; the 

 disseppiments are numerous, and the septa carinated in the outer zone through 

 which both sets of septa extend; a few disseppiments are present in the more 

 open, central zone penetrated only by the longer septa. A few of the corallites 

 — about 1 out of even' 5 in the same corallum. — show a small central area 

 about 1 millimeter in diameter surrounded by a distinct wall formed by the 



