5 2 



HARDJVICRE'S SCIENCE-GOSSIP. 



very earnestly amongst my material, and I have been 

 rewarded by finding some surrounding the cell 

 mouths — others attached to the spiniferous processes 

 of Fenestella, and some few attached to the spiniferous 

 and infertile branches of Fenestella and Polypora. 



To the Fenestella other small processes were at- 

 tached, and wherever they exist they are generally 

 developed, but not always, on the margins of the frond. 

 Some of these are of a spine-like, or rather of a hook- 

 like character : and these hooks are always turned 

 towards the margin whence the processes are de- 

 veloped. On other parts of the polyzoary — some- 



of recent polyzoa — as was served by Pala;oeoryne in 

 the ancient group. 



The reproductive history of Fenestella generally 

 seem to me to follow any co-ordinate type of the 

 genus. The same character in the cell, the same idea 

 prevalent in the Palseocoryne and in the spiniferous 

 and infertile branches, and the same character of the 

 bifurcations exist in one species as in the others ; but 

 there are certain peculiarities about F. plebeia that 

 are apparently absent in other forms. 



The corallum (or polyzoary), says M'Coy, was 

 flat, expanded, and fan - shape ; thickly carinated 



Fig. 42. — Vertical and horizontal s:ctlon of shale containing F. p'.e'xict, M'Coy. Natural size. 



*"'£• 43- — The broken edge of Fig. 1, reversed ; the \ refers to the continuation on the same 

 plane of the polyzoon — slightly different at c. 



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Fig. 45. — Spiniferous branch 

 of Polypora tubcrcitlata. 

 (Hairmyres.) 



v^-" 



Fig. 44. — Enlargement of infertile roots and branches as at a in both 

 figures, at X, Pakeocoryne, and infertile processes are developed, 

 pointing upwards. Branches and root-like process slightly exagge- 

 rated. 



times in the front, sometimes on the back, other 

 processes are developed, of a character altogether 

 different from these spiniferous branches. These are 

 the Pal&ocoryne both radiata and Scotica of Duncan. 

 Singularly enough these have been placed among the 

 Hydrozoa, and characters given by him to separate 

 parts altogether at variance with the facts. Palaso- 

 coryne, however, are unique appendages, and they 

 indicate another method of reproduction — peculiar to 

 the fenestrate forms of polyzoa found in the palaeo- 

 zoic rocks. Neither the appendages of Bicellaria 

 tuba, nor the anomalous ones of Bimeria in any way 

 resemble — or serve similar purposes in the life-history 



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Fig. 47. — Diagram of Palaeo- 

 coryne, showing that the 

 Fenestella cells are con- 

 tinued along the base of 

 the processes, and are not 

 covered up by them. (By 

 Mr. John Young.) 



Fig. 46. — Sketch of branch- 

 ing spiniferous process on 

 frond of Fenestella, from 

 Cragenglen- Campsie, 

 Scotland (four times natural 

 size). By Mr. John Young. 



interstices, with thin and regular dissepiments. The 

 fenestrules were equal and rectangular, from two to 

 three times as long as wide, with a width equal to 

 that of the interstices. There are four or five cell 

 pores to length of fenestrule, with slight prominent 

 margins, about the diameter of the cell apart. The 

 reverse of the interstices are minutely granulated, and 

 very coarsely sulcate longitudinally. 



