88 On SpecAes o/"Ascodictyon rtwc? Rliopalonavia. 



of the stoloniferous Vesiculariidse, such as Vesicularia and 

 BowerhanMa^ or, possibly, some member of the more humble 

 race of the Entoprocta. Barrois has already, in his ])aper " On 

 the Embryogeny of the Cyclostomatous Polyzoa " (Ann. & 

 Mag. Nat. Hist. Nov. 1882, p. 402), spoken of a pro-Bryozoan 

 race, composed of " free swimming organisms." May Asco- 

 dictyon be the attached, or larval tbrm, of some of the as yet 

 unknown pre-Upper- Silurian types of organic life, polyzoan 

 or otherwise ? 



There is, however, another suggestion which may help to 

 throw some little light on the development of A. radiciforme^ 

 Yine, though we cannot hope by the comparison to explain away 

 all the difficulties which surround the subject. I refer now 

 especially to some remarks contained in a paper by Mr. George 

 Busk, F.E.S., entitled "Notes on a peculiar Form of Poly- 

 zoa closely allied to Bugida, =Ki?ietoskias, Kor. & Danielsf e i " 

 (Quart. Journ. Microsc. Soc. vol. xxi. new ser.). After 

 speaking of the development of the various species of Kineto- 

 skias, Mr. Busk says, " I have yet scarcely adverted to the 

 most rem.arkable feature of Kinetoskias, viz. the peduncle or 

 stem, which appears to exist in all species. . . . The mode of 

 formation of this part of the zoarium, which is undoubtedly 

 the homologue of the bundle of separate radical tubes so 

 commonly met with among the Polyzoa, is extremely curious 

 and interesting, and, at the same time, in some points as yet 

 more or less obscure, as, in fact, 7nay he said resjjecting the 

 mode of formation and development of the more ordinary form 

 of radical tubes'^. 



" In the more common forms they are cylindrical, jointed, 

 chitinous tubes, with rather thick walls and with very scanty 

 contents, beyond a few granular particles and irregular 

 threads, representing, as it would seem, the remains of an 

 endosarc, with which, in order that their progressive increase 

 in length, and occasionally complicated branching &c,, may 

 be effected, we must suppose the tube to be furnished. In 

 fact it is otherwise impossible, without assuming the presence 

 of a germinal material, to account for the fact that even after 

 the tubes have attained a considerable length the extremity, 

 or a considerable part of the tube, may undergo great changes 

 in form, as is seen in the production of hooks and other means 

 of ensuring adhesion to foreign bodies, changes showing a 

 most extraordinary adaptability to circumstances. Not the 

 least remarkable of these adaptations is the division of the 

 extremity of the tube into a multitude of yqtj minute tubular 



* Italics mine. 



