700 
DR W. T. GORDON ON CAMBRIAN ORGANIC REMAINS 
surface was minutely papillate, but the papillae did not each correspond to a single 
intervallar tube. In one part of one of the specimens the outside lay on the exterior 
of the limestone, and a photograph is shown in PI. V, fig. 49. The hexagonal character 
of sections of the tubes is well shown, but the level is too far below the actual surface 
to indicate the papillate character of the outer wall. The material was too limited 
to admit of sections being prepared to show the inner wall, etc. ; but such sections as 
were made indicate that the 
inner wall is not papillate 
but smooth, and that the 
pores are the inner ends of 
the tubes. 
The walls of the tubes 
are also porous, but the pre- 
servation is not very satis- 
factory. The best examples 
are in figs. 43 and 48, w.p. 
Here the pores are seen to 
be in two rows, and about 
5 or 6 occur per mm. This 
character alone would dif- 
ferentiate S. gracilis from 
S. favus, the only other 
known species which has 
three rows of pores on each 
wall and 3 pores per mm. 
The main distinctions, how- 
ever, lie in the very narrow intervallum in S. gracilis , from 1 to 1-4 mm., and in 
the narrow diameter of each tube, -4 to -5 mm. In S. favus the corresponding- 
dimensions are 5 to 6 mm. and 1 mm. respectively. 
The vesicular zone near the inner wall is not so marked in S. gracilis as in S. favus. 
In the latter type it is due to the great length of the tubes so that, where they bend 
down near the inner wall, several are cut through in any transverse section, and a 
broad, apparently vesicular zone formed. 
Another interesting point shown by the new species is a coralloidal type of infilling 
towards the base of the cup, and an irregularity in the tubular arrangement. The 
new species may be defined as follows : — Cup conical ; intervallum narrow (l mm. 
to 1’5 mm.). Outer wall papillate, one pore on apex of each papilla. Pores lead 
into tubes (maximum diameter ’5 mm.) hexagonal in section, lying horizontally 
between the walls. End of tube bent down near inner wall. Inner wall smooth, 
perforated, each pore the inner end of a separate tube. Apparent vesicles near inner 
wall due to sections of bent part of more than one tube. Vesicular zone of one row 
Text- Fig. 1. 
a. Spirocyathus atlanticus. c, Syringocnema gracilis. 
b, Syringocnema gracilis. d, do. 
e, Coscinocyathus fultus. 
