34 PROCEEDINGS OF THE 



of the gemmuliferous vesicles, often seen overlying the cell apertures 

 of recent polyzoa, and, in plate v., fig. 11, he illustrates the position 

 of these small vesicles or pores in their relation to the cells. He 

 also, in fig. 8 of the same plate, illustrates what he terms the foramina 

 or small pores, on a portion of the non-celluliferous or reverse face 

 of the frond, but he omits to say anything about these small pores 

 on this face, in his description of the species in the text. There 

 cannot, I think, however, be the least doubt, although previously 

 overlooked, that in the occurrence of these small pores or vesicles 

 amongst the ordinary cells of the poriferous face, and likewise in the 

 foramina or pores on the reverse face, we have here a good character 

 in this genus, that more closely allies our Carboniferous Synocladia (?) 

 with the Permian Thamniscus than it does with the typical Permian 

 species of Synocladia, in which these characters are absent. Tham- 

 niscus, however, as pointed out by Prof. King, differs from Syno- 

 cladia in its manner of branching, and in not having the branches 

 or interstices connected by dissepiments, except in doubtful or very 

 rare instances. The Carboniferous forms of Synocladia (?) in being 

 fenestrated are likely to be yet ranked in a different genus from 

 that of Thamniscus, although, from the characters I have here 

 pointed out, it will be seen that they have had a close zoological 

 relationship. While discussing this subject, I may also refer to 

 another Carboniferous polyzoon which Dr. Young and I figured 

 and described in the Annals and Magazine of Natural History for 

 May, 1875, and which we referred doubtfully to Thamniscus (?). 

 I am now, however, satisfied that what we then described as T. (?) 

 Rankini, must now be placed in a different genus from Thamniscus, 

 as a recent examination of many well-preserved specimens shows 

 that it has none of the small pores or foramina on either face of the 

 polyzoarium, which, Prof. King says, is one of the distinguishing char- 

 acters of his genus. T. (?) Rankini has many external characters 

 which closely relate it to the recent Horner a, but this is a genus 

 which has not yet been admitted into the group of Carboniferous 

 polyzoa, although it would seem to be a natural and proper resting- 

 place for this form. There is also another Carboniferous polyzoon 

 from our strata, not yet described, and also very closely allied to 

 Hornera, so that when the time for revision arrives, we shall be 

 necessitated either to admit Hornera amongst the Carboniferous 

 genera, or to establish a new genus for these forms. 



It will be seen from the foregoing remarks, that there is at present 



