2'68 Mr. J. Young on the Structure of 



occurrence of two short spines that project, one on each side, 

 from the raised lower lip of the cell ; 2nd, that the cell-mnuths 

 are seen to be closed by a thin calcareous cover (or operculum) 

 which I then considered to be the commencement of tabulse 

 in the cells ; 3i'd, that in the spaces (interstitial) between the 

 cells there are also numerous small polygonal cells that are 

 arranged in from one to three rows ; 4th, that we often find in 

 the several stages of the organism that these smaller cells are 

 closed by a thin calcareous outer layer, which leaves only the 

 larger cell-openings visible. These characters I stated had 

 been formerly noted by myself in a paper in the Glasg. Geol. 

 Soc. Trans, vol. vi. p. 213 (1879). 



In the ' Annals' for Dec. 1885 there is a paper by Prof. 

 H. Alleyne Nicholson, M.D., and Arthur H. Foord, F.G.S., 

 "On the Genus Ftstulipora, JVl'Coy," with figures and 

 descriptions of several species. In that paper T am glad to find 

 that my identification of M'Coy's Fistulipora in its younger 

 and older stages was admitted by the autliors, and further 

 that they had been able to show, from an examination of the 

 type specimen, that Phillips's earlier described Calamopora 

 incrustans was identical with F. minor^ M'Coy, Piiillips's 

 species thus becoming the type of the genus Fistulipora^ 

 M'Coy. _ 



In their remarks upon F. incrustans^ PhilL, as well as on 

 the other species of the genus which they describe, I observe 

 that Messrs. Nicholson and Foord fail to notice some of the 

 external characters seen on the surface of the type species and 

 which are noted in my paper in the ' Annals.' As I con- 

 sider a knowledge of these characters to be essential, and of 

 importance to any one studying the structure of the organism, 

 also for enabling them to form some opinion as to its zoo- 

 logical relationships, I again take the liberty of bringing the 

 subject before the readers of the ' Annals,' pointing out in 

 more detail the characters I had already noted as well as one 

 or two other ii^ternal structures that I have found in the Car- 

 boniferous FistuJiyora since my paper appeared, all of which 

 I have been able to verify in well-preserved specimens and 

 in numerous sections that I have prepared for microscopic 

 examination. 



1 may first remark, with regard to the trilobed form of 

 the cell-mouths in the autopores of Fistulipora^ that this is 

 not a character that is exclusively confined to this genus, as 

 Mr. E. O. Ulrich figures and describes several forms, in 

 a paper in the Journ. of the Cincin. Soc. of Nat. Hist, for 

 April 1884, as American genera of Bryozoa that have the 

 same trilobed form of cell-mouths in their autopores, with an 



