174 Dr. H. A. iS'icliolson and Mr. R. Etlieridge, Jun., on 



SiJec. char. Corallum branched, of cylindrical or com- 

 pressed stems, from 1\ to 3 centlra. in diameter. The 

 corallites diverge from a central line, or radiate nearly at 

 rio-ht angles from botli sides of a median plane. The coral- 

 lites are long-oval, rounded or suLpolygonal in shape, from 

 ^ to ^ millim. in diameter, more or less. The walls are thick- 

 ened, and show no clear line of demarcation between adjoin- 

 ing tubes. Tabula? few and remote. Mural pores doubtfully 

 detected. " Acauthopores" * are developed at the angles of 

 junction of the corallites, but are comparatively few in 

 number and of large size ; they appear at the surface in the 

 form of blunt spines. In the axis of the corallum the coral- 

 lites are polygonal, but they become more or less cylindrical 

 as they diverge outwards, and in the peripheral region they 

 are annulated with numerous close-set periodical thickenings. 



Obs, In our former memoir upon Stenoijora (Joe. cit.) we 

 identified with the present species certain examples of a 

 Stenopora which had been submitted to us by Mr. Jack, from 

 the Permo-Carboniferous rocks of Queensland, and which we 

 had carefully examined by means of thin sections. Our iden- 

 tification rested upon the fact that the specimens in question 

 ao-reed entirely in external form and in macroscopic characters 

 with the Strzeleckian type of S. ovata, Lonsd., preserved in 

 the British Museum. We have, however, now been able to 

 make a microscopic examination of thin sections of the type- 

 specimen of S. ovata, and we find that in spite of the close 

 external resemblance which it bears to the Queensland speci- 

 mens, its minute structure is entirely different. The above 

 definition of this species is therefore based upon the type- 

 specimen of 8. ovata, and not upon the Queensland examples, 



* Most of the species of Stenopora are provided Avitli the siDgular 

 modified coralhtes for which the name of " acauthopores " has recently 



are exceedingly characteristic of the Mouticuliporoids. This fact, taken 

 along with other marked resemblances between the StenoporcB and certain 

 of the Monticiiliporoids, has led ns to think that too gi-eat weight haS per- 

 haps been attached by De Koniuck, as also by onrselves, to the value of 

 the " mural pores " as a character of classificatory value. There can be 

 no doubt that the walls of the corallite'^ in some (and probabl}' in all) 

 of the species of Stcnoporce are pierced by irregular mural pores, and heuce 

 we have formerly referred the genus to the Favositidfe. In all other 

 points except this the species of Sfeno^mra are, however, most nearly 

 related to the Monticuhporoids. The question therefore arises whether the 

 Stenoporce might not with propriety be regarded as an independent group 

 of Corals (probably A.lcyonarian), resembling the Mouticuliporoids in their 

 general characters, but having perforate walls. 



