54 



HARD WICKE'S SCIENCE- G OS SIP. 



the fronds of F. plebeia would be correspondingly 

 large ; but if the waters were surcharged with fine 

 mud-like particles, like the Welsh shales, then these, 

 falling upon the recumbent life form would soon 

 bury itself out of sight. In the one case the frond 

 would be perhaps from three to five inches square, in 

 the other perhaps not more than one inch. The 

 mystery of development is apparent in this recum- 

 bency, and we have no better example of the battle 

 of life in the whole palaeontology of the older rocks 

 than is to be found in the life history of these 

 palaeozoic polyzoa. 



During the last twelve months I have examined a 

 vast number of the fronds of F. plebeia, and I find 

 everywhere that the inequalities of the surface add to 

 the grace of the Fenestella. Here there is a dead 

 Productus,* there some fallen encrinal stems, im- 

 bedded in the mud. Over these the delicate polyzoa 

 weave their beautiful polyzoary, adapting themselves 

 gradually to all the undulations of the surface. Not, 

 however, passing over the shell or the stem with 

 that sharpness or splint-like character which would 

 exist had the polyzoary been developed in an upright 

 position— but delicately weaving their network even 

 into the angles formed by the rounded stem as it lay 

 in contact with the bottom. In no place is the poly- 

 zoary doubled upon itself so far as I am aware. 



In figures 42 and 43, I have given an outline of 

 the fractured shale of the natural size of my specimens. 

 The continuous outlines are the shape of the block, 

 while the dotted ones represent the exposed edges 

 of the Fenestella. The marks in both figures are 

 parts of the same polyzoary on the same plane, only 

 one represents the right-hand fragment, while the 

 other is the left-hand fragment reversed. There is a 

 slight difference in the one that is not found in the 

 other (c, fig. 43). At a in the two figures there are in- 

 fertile processes of a root-like character, enlarged in fig. 

 44 to show their connection with layers of the polyzoary 

 on certain planes. The character of these root-like 

 processes will be considered further on. At the upper 

 surface at point a, fig. 44, Palaeocoryne is developed 

 on the under part of the frond, and the poriferous face 

 just at this particular point is much confused in cha- 

 racter ; portions of the branches, with several bi- 

 furcations, turning towards each other and meeting 

 in a rounded form at the top. This, however is a 

 peculiarity at this one point only, otherwise the frond 

 is amply and admirably developed on other parts of 

 the same plane. Here, at least, Palaeocoryne serves 

 the purpose, not only of the supporting of the poly- 

 zoary, but actually of passing over the reproductive 

 power from one stage to another higher up, producing 

 the uppermost dotted portion of the frond at a in 

 figs. 42 and 43. From the peculiar character of F. 

 plcbcia at this point, I am inclined to the belief that 

 this is only one of many points where this energy 



* Longispinus. 



exists on this particular plane. There was a dis- 

 turbing cause, and this too has left its stamp upon 

 the shale. A large productus ^settled down upon the 

 polyzoary, burying a portion of the frond and forcing 

 by its unpleasant presence either death or new 

 development upon the polyzoa. 



By the possession of these singular appendages, 

 Palaeocoryne, the colony was saved from destruction 

 and development was carried on a stage higher up. 

 In another piece of shale I have specimens of 

 F. plebeia, on two planes. Here Productus longispinus 

 is the original tenant, and where Palaeocoryne passes 

 over the life form from the lower to the higher, no 

 confusion whatever takes place in development of the 

 polyzoary ; and in another specimen where there is no 

 disturbing influence the frond, or rather the polyzoary, 

 is beautifully developed, with that flat, expanded fan- 

 like character noticed by M'Coy in his description 

 of the species. 



By the careful measurement of the exposed sections 

 of Fenestella by the compass, on fig. 42, I obtain a - 

 length of about fourteen inches, and this multiplied 

 by three, which is considerably less than the average, 

 gives a surface of about forty-two superficial inches — 

 an idea of Fenestella growth altogether different from 

 that generally entertained as to the capacity of the 

 genus. 



Many of the earlier of Mr. Shrubsole's Welsh 

 Fenestella plebeia I was inclined to place under the 

 descriptive character of Phillips' sp. F. flabellicla ; but 

 as specimen after specimen began to show characters 

 altogether different from Phillips' diagnosis, I declined 

 to place any more with that species. After breaking 

 up my shale, I forwarded a small portion of it to 

 Mr. John Young, F.G.S., of the Hunterian Museum, 

 Glasgow, and he kindly identified the specimen as 

 a fragment of F. plebeia (M'Coy). He also stated 

 in his letter (July 7, 1878), that "It would be an 

 interesting point to prove, in a satisfactory manner, 

 that Fenestella and other kindred forms of fenestrated 

 polyzoa grew in a recumbent method over the car- 

 boniferous old sea bottoms. One would be inclined 

 to think, that from the small size of the roots com- 

 pared with the large size of the fronds in many of the 

 species, that the recumbent method was their natural 

 way of growth." So far as I am acquainted with the 

 subject there is no literature extant respecting this 

 idea, and I believe Mr. Young is equally ignorant of 

 any. The description and the figures of my slab will 

 be, I believe, sufficient to prove the habit of the species, 

 and any doubt respecting the true interpretations of 

 the facts can be satisfactorily corrected by a reference 

 to the fossils which I shall continue to keep in my 

 possession. 



I shall now take Palaeocoryne in all its stages, and 

 endeavour to identify the whole as generative processes 

 of the fenestrate polyzoa. 



Attercliffe, Sheffield. 



( To be continued.) 



