278 
MR. A. W. WATERS ON SOME 
the growing end the zooecial tubes are more or less angular, and 
down each side there is a row of rather small pores (fig. 3) ; 
as growth proceeds, calcareous matter is added in ridges both on 
the front and back surfaces, and then these small pores are left 
at the bottom of the pits. I figured and referred to these pits 
in Hornera frondiculata in the Quart. Journ. Geol. Soc. vol. xl 
p. 677, pi. xxx. fig. 8. 
The external structure of the growing ends of the outside is 
the same as seen in the inside in other parts when broken down, or 
when sections are made. The position of the interzooecial pores 
is often very characteristic, and can also sometimes be used in 
fossil species. These internal pores may be in parallel rows 
close together or far apart, and may be approximately regular 
or irregular; and the distance apart is a point of great import- 
ance ; but as yet little attention has been given to these pores 
in published papers. An absolute regularity does not seem ever 
to occur ; but the plan can very frequently be seen. 
There is one structure which lam not able to explain. In the 
interior of the zooecial tubes there are several protuberances 
projecting forwards (fig. 7), either short or half as long as the 
width of the zooecial tubes, and much curved forwards. They 
do not seem to be the commencements of “ closures,” aud 
whether they are used for attachments cannot be decided from 
my dried specimens. Although I have sections of a very large 
number of Cyclostomata, I have not come across anything of the 
kind before. It does not seem likely that it should be compared 
with the rays of Entalophora intricaria , Lichenopora , and Hetero- 
p or a (see Quart. Journ. Geol. Soc. vol. xliii. p. 340, &c.) ; but 
both are as yet unexplained. In the coarsely pitted structure 
this species resembles Idmonea radians , Lam. ; but the genus 
Idmonea visually has a finely punctured surface. 
The zooecia are arranged in very distinct series, suggesting at 
first Idmonea ; but the serial arrangement is not uncommon in 
Hornera ; for in H. lichenoides it occurs decidedly in some spe- 
cimens, and in the fossil H. concatenala, Ess., aud H. serrata, 
Ess. (non d’Orb., non Menegh.), it is very marked ; again in 
H. lichenoides the amount to which the zocecial tubes are exserted 
is variable, and no doubt this and H.fissurata are closely allied. 
Idmonea Meneghini, Heller. (PI. XIV. fig. 2.) 
The ovicell taking the place of one of the lateral series is a 
