TIYDROCORALLINE GENUS ERRIXA. 891 



General Remarks on Structure. 



Gasteropores. — Before concluding this account of these species 

 I may refer briefly to one or two results of a negative character 

 that I have obtained. It occurred to me that if the speci- 

 mens I examined belonged to different species, there might be 

 some measurable difference to be observed in the styles of the 

 gasteropores. The style is in all cases like an elongated and 

 sharply pointed brush, but careful and constantly repeated com- 

 parisons of the styles of the gasteropores of different specimens 

 revealed no characters by which they could be distinguished. 

 The type of style is the same in all the specimens, and although 

 the brush is more slender in some cases than in others, there is a 

 greater range of variation in this respect in the gasteropores of 

 a single specimen than there is in the gasteropores of different 

 specimens taken at random (PI. XCVl. figs. 14 & 15). 



The way in which it is possible to study the shape of the 

 gasteropore styles is to make a vertical fracture in a plane parallel 

 with the long axis of a branch. In a large percentage of such 

 fractures the whole length of at least one gasteropore with its 

 style will be exposed. 



In such fractures it may be observed that some of the gastero- 

 pores extend as far down as the axis of the branch, but in others 

 they extend only a short distance below the surface. In the long 

 gasteropores the style can be traced right down to the base of the 

 pore, but it is usually supported by one or, in some rare cases, 

 more than one, tabula (fig. 14) similar to the tabulse described by 

 Miss England (5) in the gasteropores of Spini^joirc. In the short 

 gasteropores the style ends abruptly at the base of the pore and 

 is not supported by a tabula (fig. 15). 



In order to make any scientific use of this character in the 

 classification of the species it would be necessary to make a large 

 iiumber of fractures, and for that purpose I have not sufiicient 

 material. 



The results I have obtained on the few fractures I have made 

 are as follows : — 



In Errina (L.) novce zelandice facies " Ramosa " and facies 

 " Cooki" the gasteropores (I have observed) are long and exhibit 

 a tabula. In the same species f^icies " Benhami " the gasteropores 

 are short, and the same is the case in the facies " Dendyi." In 

 Mr. Morgan's specimen of Errina (Z.) aspera the gasteropore is 

 also short. In Errina {L.) cajmisis the gasteropores are short, 

 extending only a little way beneath the surface. As to this 

 character in the gasteropores of the other species I have no 

 evidence to bring forward. 



My conclusions, from this evidence, are that the length of the 

 gasteropores and the presence or absence of a tabula are not, at 

 present, characters of any value for purposes of classification. 



Gonojjhores. — All the specimens I have examined show ampuUte. 

 They can usually be seen on the terminal branches as shallow 



