200 Mr. H. J. Carter on the Polytremata. 



the sarcode creeps witMn the intraseptal spaces, it is evident 

 that on canal-system was present in this instance, any more 

 than in Polytrema miniaceum, where the only network in the 

 interspaces between the chambers appears to me to be that 

 which I have described in P. miniaceuvi as the centre of the 

 lines forming the subhexagonal structure on the surface of the 

 older test (Pi. XIII. fig. 6, /),well represented by Max Schultze 

 in his figure of an "Acervuline Planorhulina^^ copied into 

 Carpenter's 'Introduction' (pi. xiii. fig. 1). So this inter- 

 septal space must be something else. 



Perhaps the chief point of difference between P. balaniforme 

 and P. miniaceum is that the hollow pillars supporting the 

 concentric foraminated (spiral ?) layers in the latter are repre- 

 sented by solid ridges of test-material in the former, which, 

 radiating continuously downwards from the hollow vertical 

 columella as the layers of the spiral lamina increase, give 

 rise to the form and direction of the triangular cavities, which, 

 subdivided by subordinate septa of the same kind, distinctly 

 represent the chambers of a foraminiferal test. Whether the 

 ridges of solid structure have been solid from the commence- 

 ment, or, like the pillars of P. miniaceum, were hollow first 

 and then became solid afterwards, my specimens of P. hala- 

 niforme, as they are all full-grown, do not enable me to 

 determine. 



Furthermore, it is remarkable that, although Dr. Carpenter 

 in his ' Introduction ' frequently compares Polytrema with 

 Carpenteria, he never once mentions Polytrema in his generally 

 excellent description and illustrations of Carpenteria ; while 

 in reference to Dr. Gray's suggestion " that Polytrema might 

 be especially related to Carpenteria^'' Dr. Carpenter observes 

 it is " an idea which is not confirmed by examination of the 

 internal structure of those types" (Introd. p. 235). That, 

 however, Dr. Gray was right may be gathered from my 

 descriptions of Polytrema miniaceum and P. halanifoi^me 

 respectively. 



But when we come to the following passage respecting the 

 presence of sponge-spicules in Carpenteria and not in Poly- 

 trema, viz. " it is a fact of some importance with regard to the 

 presumed spongeous character of the body of Carpenteria, that, 

 although (as will be presently seen) the openings at the ex- 

 tremities of the branches of Polytrema communicate very freely 

 with the chambered interior, I have not been able to find the 

 least trace of the spongy parasite in its substance " [op. cit. 

 p. 236), we not only realize the force of Max Schultze's obser- 

 vation before quoted ('Annals,' 1863, vol. xii. p. 419), viz. that 

 '' by this means Carpenter establishes a sharp distinction 



