278 SIDNEY F. HARMER. 



the calcaroons wall (fig. 32), and pass vertical!}' to the 

 epitheca. Basallj these tubercles are longer and are rather 

 more regularly arranged. Their arrangement is seen in 

 figs. 34 — 36, from which it is apparent that they serve to 

 keep the epitheca stretched out at a considerable distance 

 from the calcareous part of the zooecium. In my preliminary 

 note (1901, p. 16) I have pointed out that there is evidence 

 that many Cretaceous Cheilostomes were provided with a 

 basal epitheca, as is indicated by the presence of calcareous 

 papillte resembling those of E. obtecta. It may perhaps 

 be suggested that a function of the epitheca is to protect the 

 calcareous Avails from the attacks of boring organisms (e. g. 

 the Infusorian Folliculina) which infest many calcareous 

 Polyzoa, 



The calcified wall of E. obtecta shows no trace of the 

 bar-like arrangement so characteristic of E. clathrata. It 

 is, on the contrary, a continuous calcareous film, traversed 

 by pores. As in the other species, these pores partly form 

 communication-pores traversing the partition-walls between 

 zooecia, and they are partly in relation with the space 

 beneath the epitheca. It is hardly necessary to point out 

 that in neither case are they open pores, although the cal- 

 careous matter is deficient in these regions. The portions of 

 the vertical walls which are actual partition-walls are of 

 limited extent (fig. 36), so that but few of the pores are com- 

 munication-pores (c. 2^.) between zooecia. I have seen no 

 evidence that the number of these is restricted to eight, as 

 stated by Waters (1896, p. 282). The majority lead to the 

 spaces beneath the epitheca, particularly to that on the basal 

 side of the frond (figs. 35, SQ). They are less numerous on 

 the frontal side (fig. 36). 



The marginal part of the frond may be strengthened by a 

 system of bars (fig. 37) which recalls those already described 

 in the zooecia of E. clathrata. This system makes its 

 appearance first in the angle between the two lobes of a 

 bifurcation, and begins as a set of regular calcareous bars, 

 running near the frontal surface, and originating from the 



