MlitUTE STRUCTURE OF STROMATOPORA AND ITS ALLIES. 193 



apart by a vertical system of delicate calcareous rods, giving rise 

 to a system o ' more or less quadrangular 'tubes." In the ' Ee- 

 port on the Palaeontology of the Province of Ontario ' (1874), the 

 same opinion is repeated; and in the 'Palaeontology of the State 

 of Ohio ' (vol. ii., 1875), the author describes several additional 

 species of Stromatopora^ and founds the genera Syringostroma and 

 Dictyostroma. 



In the 'Dawn of Life' (1875), Principal Dawson incidentally 

 gives the result of his observations on the structure of Stromato- 

 pora and its allies, apparently regarding them as intermediate be- 

 tween the Foraminifera and the Sponges. This distinguished 

 palaeontologist further describes in Caunopora and Coenostroma a 

 system of tubes or groups of tubes which traverse the horizontal 

 laminae of the skeleton, and " in each successive floor give out 

 radiating and branching canals exactly like those of Eozoon^ 

 From Dr. Dawson's description and figures, we should be disposed 

 to imagine that in this statement he is referring to the compa- 

 ratively large radiating and vertical canals which are present in 

 most, if not in all, of the Stromatoporoids, and which are, as a 

 rule, visible even to the naked eye. If, however, he is referring 

 to any microscopic tubules at all comparable to the minute 

 "tubuli" of the test of the perforate Foraminifera, then we can 

 only say that though w^e have in some thin sections imagined 

 that we had met with indications of such a tubulation of the 

 skeleton, we have hitherto failed, after the most careful inves- 

 tigation, to satisfy ourselves as to the real existence of such a 

 structure. 



In a memoir upon Stauronema, a new genus of fossil Hexacti- 

 nellid Sponges (Ann. & Mag. Nat. Hist. ser. 4, vol. xix.), Mr. 

 Sollas places ^iromatopora concentrica (under the new generic 

 title of Callodictyon) among the Vitreo-hexactinellid sponges, 

 in the family Aphrocallistidae. In a subsequent paper (" The 

 Structure and Affinities of the Genus Siplionia,^' Quart. Journ. 

 Geol. Soc. 1877), the author says that he does not regard the genus 

 Stromatopora as wholly referable to the Vitreo-hexactinellidse, 

 but that part is Hydrozoal and related to Millepora and Rydrac- 

 tinia, and that part belongs to other groups not yet determined. 



Mr. Carter (Ann. & Mag. Nat. Hist. ser. 4, vol. xix. 1877) 

 has expressed the opinion that Stromatopora and allies are closely 

 related to the living genus Hydractinia, and that the extinct 

 genus Farlceria, described by Dr. W. B. Carpenter as a Forami- 



