16 BRITISH STROMATOPOROIDS. 



ramify through the skeleton of Millepora, and are regarded as being essentially of 

 the same nature. 



In a succeeding number of the same publication (' Ann. and Mag. Nat. Hist.,' 

 ser. 5, vol. i, p. 412), Mr. Carter has a short note on " Calcareous Hexactinellid 

 Structure in the Devonian Limestone," in which he describes specimens from the 

 Devonshire Limestones as showing a structure apparently similar to that of the 

 Hexactinellid Sponges, but calcareous in composition. The specimens in question 

 belonged, doubtless, to Stromatoporoids appertaining to the genus Actinostroma, 

 some of these, when examined in certain aspects, presenting an appearance very 

 similar to that of some of the Hexactinellidce. 1 



In a still later number of the same publication (' Ann. and Mag. Nat. Hist.,' 

 ser. 5, vol. ii, p. 28), Principal Dawson opposes the views expressed by Mr. Carter 

 as to the relationships which the latter sought to establish between the Stromato- 

 poroids and Millepora. 



Later again (' Ann. and Mag. Nat. Hist.,' ser. 5, vol. ii, p. 304, 1878), Mr. 

 Carter returns to the same subject in a paper entitled " On the probable Nature 

 of the Animal which produced the Stromatoporidm, traced through Hydractinia, 

 Millepora alcicornis, and Gaunopora to Stromatopora." Much of this memoir is, 

 in the main, a repetition of points which had been brought forward by the author 

 in previous communications. Mr. Carter explains that in former papers he had 

 spoken of Gaunopora, Phill., under the name of Stromatopora, and he has now 

 come to the conclusion that Gaunopora is really intermediate in its characters 

 between Millepora, Lam., and Stromatopora, Goldf. The tubes of Gaunopora he 

 regards as being inhabited by polypites, and as being comparable with the " gas- 

 tropores " of Millepora. 



Also in the year 1878, but prior to the appearance of most of the memoirs just 

 noted, a paper on " The Minute Structure of the Skeleton of Stromatopora and its 

 Allies," was published by Dr. Murie and the present writer (' Journ. Linn. Soc./ 

 vol. xiv, 1878). In this memoir, after a historical summary, the authors treat of 

 the general structure of the Stromatoporoids, and bring forward evidence to show 

 that the skeleton of these organisms was certainly originally calcareous. Being at 

 that time unacquainted with the minute structure of the skeleton of the original 

 specimen of Stromatopora concentrica, Goldf., the authors followed all previous 

 writers in considering the genus Stromatopora, Goldfuss, as comprising those types 

 which possess definite " radial pillars " united by periodically-developed hori- 

 zontal connecting processes. The genus Glathrodictyon was proposed for certain 

 Stromatoporoids with short and irregular " radial pillars," and two species of the 



1 It may be noted that, in certain states of preservation, the singular Coral described by Roenier 

 under the name of Chmtctes slromatoporoides, also exhibits appearances curiously like tbose shown by 

 certain Hexactinellid Sponges. This Coral occurs in the Devonian of both Devonshire and Germany. 



