394 Royal Society : — On the Distribution of 



as it does not seem natural to suppose that the former, which is 

 so essentially an Entozoon, could have been descended from a stock 

 capable of assuming solid food La the outer world. 



Dr. Carpenter unconsciously gives us the weight of his opinion 

 in the following quotations from his valuable work on the mi- 

 croscope. On page 449 he says, speaking of Sphcerozoum, 

 " Towards the inner surface of this (the outer) coat are scattered a 

 great number of oval bodies resembling cells, havmg a tolerably 

 distinct membraniform wall and a conspicuous round central 

 nucleus, thus corresponding closely with the Gregarimi type." 

 I might mention in passing that, having frequently taken in 

 the towing-net the unequivocal allies of DictifocJia with sarcode 

 bodies identical with those of Sphcerozoum, I have no hesitatioji 

 in assuming Dictyocha itself to belong rather to the ThalassicolUdsD 

 than to the group with which it is more usually associated. 

 This family is commonly included under the head of Ehizopoda ; 

 and there can be no doubt that the generalization, irrespective 

 of that term, is a correct one ; but it is a stretch of transcendental 

 anatomy to speak of the existence of pseudopodia in any member 

 of it. The radiating branched filaments within the dense external 

 investment of Tludassicolla nucleata are not extensions of the sar- 

 code' body, like those of Gromia for example, but apparently act as 

 retinacula, and as conduits for dialytic currents, which may account 

 for the phenomenon of cyclosis observed in some instances. 



Professor James-Clark, of Pennsylvania, appears to have satisfied 

 himself, at least, that there is a remarkable agreement of characters 

 exhibited between the Porifera and the Infusoria, which are 

 connected, as he endeavours to show, by a regular gradation of 

 animals. The derivation of the latter group of Protozoa from 

 the former, which I had myself assumed quite independently, is 

 therefore supported by that gentleman's researches. 



Even with our present advanced knowledge of the Infusoria 

 it is doubtful if we do not still include amongst them the larvae of 

 Turbellaria ; and, indeed, the passage from the one type to the 

 other would appear to be natural and easy. On the other hand, 

 tracing through such forms as Nemertes, Bonellia, and Priajmlus, 

 8ijnmcuh(s will lead directly to the less-equivocal Echinodermata ; 

 and here the series must wind up ; for further evolution, though 

 perhaps possible, does not appear to have taken place. 



The existence of such low or simple forms of Eotifera as the 

 genus Axjilwnchna, for example, would be favourable to the idea 

 that the JN^octilucidte might have been the progenitors of that order 

 of beings. It is of course quite gratuitous, but convenient, at 

 present to assume that the Koctilucidfe would thus hold the same 

 relationship to the Polycystina that the Infusoria appear to do to 

 the Porifera. However this may be, it is more certain that the 

 Eotifera are at the root of the annulose and articulate series. 



From the Eotifera, through the Annehda, we may thus trace 

 the development of the crustaceous and chitinous types of Arti- 

 culata like a dichotomous branch. 



