278 



MB. 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 ofteu 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 pa2:)ers. 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 

 projectiiig forwards (fig. 7), either short cr half as long as the 

 width of the zooecial tubes, and much curved forwards. They 

 do not seem to be the commencements of " closures," and 

 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 JEntalopliora intricaria, Lichen op or a ^ and Hetero- 

 jpora {^QQ 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 usually 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. concaienata, Ess., and H. serrata, 

 Ess. (non d'Orb., non Menegh.), it is very marked ; again in 

 H. lichenoides the amouut to which the zooecial tubes are exserted 

 is variable, and no doubt this and H.jissurata are closely allied. 



Idmonea Meneghini, Keller. (PI. XIV. fig. 2.) 



The ovicell taking the place of one of the lateral series is a 



