91 
ersed are raised on the upper side into little eminences. The 
distinction of layers is produced by variations in the density 
of the coralline substance. Masses of coral several feet in 
diameter; .distance of pustules 4.06 mm. (.16) ; mean thickness 
of laminse .20 mm. (.008). Occurs also at Iowa City. 
Stromatopora monticulifera. —In very large spheroidal 
masses constituted like those of S. pustulifera , but differing 
therefrom in the much larger and more remote eminences on 
the upper surfaces of the concentric beds, and in the larger 
and more distinctly radiate character of the passages which 
diverge from the apices of the monticules. These passages, 
on the exposed surface, are little flexuous, somewhat branch¬ 
ing channels which diminish in size and disappear within 5 
mm. (.2). Distance of monticules .76 mm. (.3) to 10.2 mm. 
(.4). Attains a diameter of at least 3.5 metres (12 ft.) 
Stromatopora nux. —In small, spheroidal, sometimes con¬ 
tiguous and coalesced masses, formed, unlike the foregoing 
species, by accretions on all sides. External surfaces of layers 
not pustulose. Masses occur from 25 mm. to 125 mm. in 
greater diameter. A species apparently the same occurs on 
Kelly’s Island, lake Erie. 
Stromatopora c^espitosa. —In general form resembling a 
large, csespitosely branching, cyathophylloid coral; stems ex¬ 
ternally in contact or more than 25 mm. distant. A longitudi¬ 
nal section shows the characteristic layers arching across the 
stem and resembling S. pustulifera in miniature ; a transverse 
section exhibits radiating lamellae as in Cyathophyllidae, but 
there is no outer wall, and the interior is completely filled with 
concentric circles of coralline substance, except a small perfor¬ 
ation in the center. Mural system entirely wanting, as in other 
Stromatoporae ; exterior of stem longitudinally triate. Diame¬ 
ter of stems 4.5 mm. (.18) to 7.6 mm. (.30). Occurs in masses 
two or three feet in diameter. 
This remarkable species exhibits a transition from Stromato¬ 
pora to Gyathophyllum and might well form the type of a 
new genus. 
Aulopora serpuloides. —Tubes minute, long, cylindrical, , 
sinuous; di-or trichotomously stoloniferous, often superim- | Vv /" v . c 
posed ; cell-mouths circular or compressed, generally opening 
upwards, not salient. Diameter of tubes .25 mm. (.01); length 
often 1.78 mm. (.07). 1 
Aulopora aperta. —Tubes short, often extended in double 
or triple linear series; cell-mouths not elevated, generally not 
limited on the lower or posterior side, leaving the whole 
length of the tube open. Diameter of tubes 1.27 mm. (.05). 
Aulopora conferta.— Tubes small, compressed, crowded, 
forming an incrustation ; cell-mouths slightly elevated, circular, 
erect, sub-equally distributed, presenting a remote resemblance 
to a Fistulipora. Mean distances of cell-mouths 1.78 mm. 
