878 ruoF. s. ,i. hicksox on the 



The characters that appear to me of more importance and to 

 signify a more jarofound differentiation are based upon : — 

 L Tlie texture of the surface of the corallum. 

 2. The aspect of the grooves in the nariform processes. 



Moseley described the surface of Errina as composed of a 

 compact, hard, ghstening, white, calcareous tissue, and he adds 

 tliat the canals generally are in this genus larger in proportion to 

 the size of the zooids than in most other forms, and the mesh- 

 works formed by them are comparatively wide open. Associated 

 with these two characters we usually find that the surface is 

 marked by shallow longitudinal grooves perforated by a series 

 of small apertures through which the vertical canals pass. These 

 coenosteal pores are well defined in the species of this group that 

 I have examined, and in the type specimens of E. lahiata and 

 E. ramosa they are about "05 mm. in diameter. The surface of 

 t:ipinipora is hard and compact as in Errina, and it is also 

 perforated by well defined ccenosteal pores. 



In the original description of the genus Lahiopora, Moseley 

 describes the coenosteum as being " minutely reticulate in tex- 

 ture," and in the description of Lahiopora moseleyi Ridley (10) 

 also describes the surface as being " minutely reticulate." In all 

 the specimens I have examined there is a very marked contrast 

 between the surface of the specimens now included in the Lahio- 

 pora group of species and of those I propose to retain in the 

 Errina group. 



I should prefer to describe the surface of the former group of 

 species as being " granular " rather than " reticulate." In Errina 

 (■Lahiopora) capensis it is coarsely granular and in all the other 

 species of the group it is minutely granular (c/. PI. XCVI. 

 figs. 14 & 15). Below the surface, the coenosteum is minutely 

 reticulate, being perforated by a network of small-meshed canal 

 passages (fig. 14), in contrast with the wide-meshed canal 

 passages of the Errina group. 



As regards the ' grooved spines. In the following species that 

 I have examined the groove in the spine that protects a dactylo- 

 pore is turned towards the apex of the branch on which it is 

 situated : E, lahiata, E. horrida, and E. ramosa. The groove has 

 the same aspect in E. glahra and E. carinala, if we may judge 

 from the figures given by Pourtales (9). 



In the only two specimens of the genus Spirdpora that are 

 known the grooves also turn towards the apex of the branch 

 (PL XCY. fig. 8). In the Lahiopora group of species there is 

 considerable variation in the direction of the grooves. In some 

 of them, all or nearly all the grooves are turned away from the 

 apex (PL XCVI. fig. 11), but in others the grooves are turned 

 in all directions, the grooved spines forming irregular clusters on 

 the surface (PL XCVI. figs. 12 & 13). The same arrangement of 

 the grooves occurs in Errina gracilis and in Errina macrogastra, 

 according to von Marenzeller, who writes •' Ihre Oeflfnung ist 

 nach hinten gerichtet, selten seitlich " (5), and nlso in Errina 

 Jissurota of Gi'ay (2). 



