SILURIAN FAUNAS. 221 
nized in the coralline layer at the summit of the Decker Ferry for- 
mation. It may be easily distinguished from the last species by its 
habit of growth and by the absence of the transverse corrugations of 
the walls. The two species have not been seen together in the same 
stratum, one being characteristic of the lowest and the other of next. 
to the highest bed in the Decker Ferry formation. 
CLADOPORA RECTILINEATA Simpson. 
Plate XVIL., Figs. 14-17. 
' 1889. Cladopora rectilineata Simpson, Trans. Am. Phil. Soc., n. ser., 
vol. XVI., p. 459, fig. 30. 
Description.—Corallum consisting of nearly cylindrical, occasion- 
ally branching stems from 2.5 to 8 mm. in diameter. The corallites 
are arranged in nine vertical series in the cylindrical branches; they 
are simple tubes radiating obliquely from the axis and gradually 
enlarging towards the aperture, with neither septa nor tabule. The 
apertures are wider than high, the lower side being margined by a 
shghtly-projecting lip. The apertures in adjacent vertical series are 
irregularly alternating in position. 
Remarks.—In none of the New Jersey material is the form of the 
complete corallum of this species shown, all the specimens observed 
being but broken branches, which are rarely observed to be more 
than 25 mm. in length. There may be some variation in the number 
of vertical series in which the corallites are arranged, but in all the 
specimens in which their number could be definitely counted it was 
found to be nine. The species most closely resembles C. seriata Hall, 
but in that species the apertures of the corallites are more closely 
crowded together laterally, and are more regularly alternating in 
position, so that their arrangement is apparently in spiral lines rather 
than in the straight, vertical lines of C. rectilineata. 
