SYRINGOPORID^. 209 



stages of the formation of the basal network, in which case 

 there is little likelihood of our ever seeing the upper surface of 

 the latter. Even if this were not the case, and if the basal 

 reticulation were really formed as a whole before the ascending 

 tubes began to be thrown up (as seems to have been generally 

 assumed), it may be stated with confidence that nothing short 

 of a microscopic examination of the internal structure would 

 suffice to show whether any given specimen were a young 

 Syringopora or an adult Aulopora, seeing that the macroscopic 

 characters would in either case be precisely the same. Upon 

 the whole, therefore, I cannot regard it as established that 

 AtUopora is founded upon the early stages of Syringopoi'a ; 

 nor can I accept the view propounded by Dr Lindstrom (Ann. 

 Nat. Hist, ser. 4, vol. xvlii. p. 14), that the connecting-tubes 

 which unite the neighbouring corallites of Syringopora are 

 " morphologically nothing but the stolons, no longer creeping 

 or attached, but suspended freely between the corallites." 



In its fully-grown condition, the great bulk of the corallum of 

 Syringopora is composed of essentially cylindrical erect coral- 

 lites, which are placed at variable but slight intervals, and 

 usually diverge more or less markedly as the surface Is ap- 

 proached, owing to the intercalation of new tubes. The new 

 corallites are produced either by budding from the sides of the 

 old tubes or as offshoots from the transverse connecting-pro- 

 cesses. The walls of the corallites are thick and compact, 

 surrounded superficially by a delicately-wrinkled epitheca, and 

 sometimes strengthened internally by a secondary deposit of 

 finely-laminated sclerenchyma (often in S. genic2ilata, Phill.) 

 Whether the corallites are near or comparatively remote from 

 one another, their visceral chambers are placed in direct com- 

 munication by means of hollow, usually cylindrical, horizontal 

 connecting-processes. These connecting-processes (fig. 30, a) 

 are tubular, and the anastomosing lamellae of the tabulae from 

 the visceral cavity are prolonged into them. They are there- 

 fore to be regarded as direct outward prolongations of the vis- 

 ceral chambers of the polypes, and they correspond precisely 



