4i8 ME. A. \V. WATERS ON THE RELATIONSHIPS 



seemed to me necessary, though it might have been better in the first 

 instance. However, the modification did not make a new genus, so that 

 under no circumstances could Lunulites cupulus, as proposed by Canu and 

 Bassler, be the type of the genus, for being mentioned in the 'Challenger' 

 Reports in the re-named genus, it does not replace the type, which is, 

 whatever Lamouroux mean-t for his L. radiata, an abundant form under 

 various names. 



In all probability L. cupulus will have to be placed in a new genus, partly 

 based on the long zooecia and the stout seta with a simple base. 



Tkochopoka, cCOrhigmj. (PI. 29. fig. 18 ; PI. 30. fig. 17.) 



Although I have seen many specimens of Trochopora, the state of pre- 

 servation has not allowed a satisfactory examination of the avicularian (?) 

 chambers, nor are they shown clearly in published figures. The fossils 

 readily break both along the radial and annular lines, and change of the 

 shell has taken place so that the minute structure cannot be studied. Near 

 the tubes passing through the calcareous base, and also near some of the 

 annular lines, the calcareous matter has become chalky, showing in section 

 white against the more transparent parts. In making horizontal sections 

 the radial divisions, as in fig. 18, are seen in every part of the solid interior, 

 that is to say, there is a succession of the same structure. 



The interior of the cone is filled in with a solid calcareous mass in species 

 described as Trochopora, but I have not been able to see that it should be 

 separated from Lunulites, and finding that L. conica, as described and 

 determined by Busk, from the Crag, is sometimes solid and sometimes 

 hollow, as stated by Busk, has confirmed my opinion. Specimens 6722, 

 6723, 0724, British Museum, are filled in below ami are solid, while 0718, 

 from the Red Crag of Sutton, are hollow cones about the same size, with 

 similar annular divisions and similarly worn. 



In the British Museum there are also specimens named by various 

 collectors Lunulites conica, many large like the Crag specimens ; and in 

 boxes from numerous European localities the solid and hollow forms occur 

 together. There seems ample reason for considering that Lunulites and 

 Trochopora cannot be separated generically, and further, though very difficult 

 to understand, it does not seem that a specific distinction can be made 

 between those that are solid and those that are hollow. Also we must see 

 whether the large form sometimes called uixeolala and the small one, as 

 figured by Michelin, are distinct. Further studies with freshly gathered 

 material may help us. 



A specimen of Selenaria nitida, Maplestone, in the British Museum has 

 the under surface filled in just as in Trochopora ; however, the vibracuiar 



