AND GLYPlIASTE.E.i, DUNCAN (1887). 2l»7 



three instances of fissiparity to a single case of budding; and 

 in anotlier part of the same specimen* three corallites, iti two of 

 which fission is stated to be in progress. Judging from these ex- 

 amples, it might be concluded that fissiparity was the rule and bud- 

 ding the exception ; but after a careful examination of the original 

 specimens figured t, it is my opinion that the phenomena repre- 

 sented are quite unconnected with fission, and that they are merely 

 examples, by no means uncommon in this genus, of the irregular 

 development of the septa in the corallites. 



lleference is also made in the same paper to a so-called very 

 remarkable and suggestive instance of fission in a section :|: made 

 from Edwards and Haime's type specimen now in the British Museum. 

 In this section there is an additional corallite interpolated in the 

 short distance between the part cut off" and the surface of the 

 coiallum, which is regarded as a new form resulting from the fission 

 of one of the adjoining corallites. The figures given of it (J. c. 

 pi. iii. figs. 4, 4') exaggerate the reality in favour of fission, and do 

 not properly represent the surroundings. The fact that the supposed 

 parent corallite is not in any degree larger than the normal ordinary 

 adjoining corallites, and that it is nearly entirely filled up with 

 stereoplasm, are strong points against its fission. There is also a 

 distinct interspace at the margin of this corallite, precisely similar 

 to those from which new buds are developed ; and as careful mea- 

 surements show that the new coral exactly fills this interspace, it 

 seems to me much more probable that it has grown in the ordinary 

 way from a bud than that it has been produced exceptionally by 

 fission. 



Character of the Corallites. — The individual corallites, as seen in 

 transverse section in the interior of the coralium, vary from nearly 

 circular to polygonal, according to the degree in which they have 

 been modified iDy mutual pressure. On the surface of the coralium, 

 when mature, the corallites are all polygonal ; their summit walls 

 are thickened, so that there is a well-marked, generally level space 

 between the individual calices ; in the median line of this there is, 

 in the best-preserved examples, a slightly elevated ridge, consisting 



* L. c. pi. iii. fig. 3. 



t Prof. Duncan may also be quoted against himself on the point; for whilst 

 in the explanation of fig. 3 he states that fission is in progress in two of the coral- 

 lites represented, he nevertheless says, in the text, p, 27, "that these appear- 

 ances may be the result of irregular corallite growth under the influence of 

 pressure from crowding." 



I Quart. Journ. Geol. Soc. vol. xliii. p. 27. The description of this section 

 ivS given as part of the original paper, read on December 1, 1886 ; but it is quite 

 impossible that it could have appeared in that paper, since the section described 

 was not even in existence at the time. This identical section was made at the 

 British Museum, at my request, to enable me to ascertain if the statements 

 made when the paper was read would be verified or not by a section of the 

 coral ; therefore some time subsequent to the reading of the paper in which this 

 description of it professes to have been included ! The section was shown to 

 Prof. Duncan, who introduced a description of it into his original paper, 

 without any note or bracket to indicate that the matter was a subsequent addi- 

 tion. 



