HARD WJCKE'S SCIENCE-G OSSIF. 



129 



needed before anything like perfect specimens may 

 be extracted. Tlie shale lies in heaps outside the 

 quarry, and the best pieces require to be dug out 

 from underneath ; these pieces are usually thoroughly 

 wet, and need to be dried in the sun before being fit to 

 work. In half-an-hour's time, however, they are ready 

 for splitting with the thin end of a geological hammer, 

 and each piece of shale will split into laminae as thin 

 as a shilling. Hundreds of Polyzoa will be found 

 in these shales, Fenestella, Polypora, Glauconome, 

 Pal^eocoryne, Gorgonia. It is also possible many new 

 forms may be discovered in this locality, and in any 

 ■case very perfect specimens of genera already known 

 ■are certain to reward the careful searcher. A hand 

 magnifying glass is absolutely necessary for the identi- 

 fication of many species. 



PhiUips and M'Coy have between them named 

 twenty-six species of Fenestellidse, which number 

 Mr. G. W. Shnibsole has lately reduced to six 

 absolutely defined species, to which several others 

 may be afterwards added. Apparently the structure, 

 growth, and habits of the Fenestellidse have been 



Here we find twenty species reduced to five, for 

 which the thanks of geologists are due to Mr. 

 Shrubsole. In these days there is a great tendency 

 to create new species on insufficient grounds, and it 

 must be aiding scientific knowledge if doubtful 

 species are swept away. In different stages of growth 

 the Fenestellidre present very different appearances 

 to the unaccustomed eye, and it is only by comparing 

 thousands of specimens that their true relatives have 

 been found. Pore-faced specimens of the Fenestella 

 are extremely difficult to obtain. In splitting the 

 shales, it is natural that the side of the organism 

 presenting a smooth surface should be the easiest to 

 develop, and so it proves in the case under con- 

 sideration ; the pore-faced specimens have little 

 roughnesses on the surface which cause that side to 

 adhere to the shale — hence good pieces are rare. 



Taking the commonest form of Fenestella — F. 

 plebeia — I figure it in various stages of growth. It 

 will be remarked how, as the structure developes, it 

 spreads out farther and farther, till the sides meet in 

 the full-grown creature immediately below the ro«K 



Kig. Cji.- J otesieiLi nodiiloia. 



l'"ig. 92. — Polypora J>o/yJ>orata. 



F!g. 93. — Polypora polyparatii. 



imperfectly understood ; thus young and full-grown 

 specimens of the same species have been known under 

 different names ; also pore-faced specimens have been 

 confounded with those showing the reverse side. It 

 is urmecessary to discuss the characteristics of the 

 Fenestellidas and other Polyzoa of Halkyn Mountain, 

 for Mr. Vine has recently entered very fully into the 

 subject in this periodical, but it may be of service to 

 give a tabular list of Mr. Shrubsole's species together 

 with Phillips's and M 'Coy's. 



Mr. Shrlesolf.'s Classification. 



I. Fenestella plebeia, M'Coy 



2. F. crassa, M'Coy . 



3. /•'. polyporata, Phillips 



4. F. iiodiilosa, Phillips 



5. /•". inembranacea, Phillips 



' Fenestella antigua, M'Coy. 



F. carinata, M'Coy. 

 I F.jlustriformis, Phillips. 



/•'. tinditlata, Phillips. 

 I /•'. irregularis, Phillips. 



F./ormosa, M'Coy. 

 1 F. tuberculo-carinata. 



F. laxa, Phillips. 



F. niultiporata, M'Coy. 



iF.fruiex, M'Coy. 

 F. bicellidata, R. Eth. jnn. 

 Actinostoma fenestratuin. 

 Young. 



, tenuifolia, Phillips. 

 hemisf'luera, M'Coy. 

 ibellata, Phillips. 



^_ XULllI 



|/'". tenu 

 .\F. hem 



[F.Jlab 



The interstices and dissepiments also thicken as the 

 Fenestella grows older. It should be noted that none 

 of these are from pore- faced specimens, and that the 

 drawings are of the natural size. Fig. 91 is Fenestella 

 nodulosa, which is a more delicate species than 

 plebeia, and has small nodules on the interstices. 



Polypora polyporata (fig. 92) has a much coarser 

 form J many fine specimens are found at Halkyn. 

 Fig. 89 represents the beautiful Glauconome bipinnata, 

 a form of Polyzoa which has not yet been thoroughly 

 described. 



Mr. Vine has fully explained the structure of most 

 of these Polyzoa, and Mr. Shrubsole has reclassified 

 them : in this article i v.ish to point out one of the 

 best localities for the collector to search, also to 

 explain the best manner to extricate the very brittle 

 forms from the rock in anything like good condition. 



C. Parkinson. 



Trichinae. — Having read that it is believed pigs 

 get trichinae from rats, I should like to know how 

 this comes to pass. — M. E., Upton House. 



