no 



HARD Wl CKE 'S S CIENCE - G O SSI P. 



axis, similar in many respects to an Archimedian 

 screw. There is a figure also in Page's " Introductoiy 

 Text-book to Geology," p. 8i, 



Ceriopor,\, Goldfuss. — Polypidom tuberose, com- 

 posed of numerous concentric layers ; pores round, 

 unequally placed (the JNIillepora of Phillips). 



POLYPORA, APCoy. — Expanding, interstices round, 

 branching, from 3 to 5 rows of pores, the margins 

 of which are never raised ; interstices connected by 

 thin transverse, non-poriferous dissepiments. Coral- 

 lum a delicate reticulated calcareous expansion. 



Verticillopora, De Franc. — Polypidom 

 branched, cylindrical, composed of aggregated poly- 

 gonal tubes, divided by transverse septa ; axis hollow 

 or filled. A peculiar genus, which may be probably 

 modified in course of time. There are two species 

 described and figured by M'-'Coy : one abnormis, 

 Lonsdale, the other ditbia, M"^Coy. 



ViN'CULARiA, De Franc. — This is a beautiful and 

 delicate genus, several species of which Eichwald has 

 figured and described in his " Palxontology of 

 Russia." The only generic description that I have is 

 this: "without lateral branches, and having more 

 than two roM's of pores." 



Carixella. — This is a new genus of Carboniferous 

 Polyzoa. "The characters, which are particularly con- 

 stant and well-marked, assign to it a position between 

 Feiicstdla and Polypora. Polyzoarium composed of 

 angular, irregularly-disposed anastomosing branches, 

 strongly carinate on both aspects, but celluliferous 

 only on one, apparently arising from a common root. 

 No regular dissepiments ; the branches bifurcate and 

 reunite with one another to form hexagonal, pentago- 

 nal, or polygonal fenestrules, often of most irregular 

 form."* 



Hemitrypa, Phillips.— a stony cup-shaped net- 

 work, keeled and poriferous as in FcucstcUa, covered 

 with an external (imperforate ?) sheath. 



IcHTiivoRACHls, M'Coy.— A straight central stem, 

 having on each side a row of short simple branches or 

 pinnce, all in the same plane ; obverse rounded, without 

 keel, each bearing several rows of small prominent 

 oval pores, arranged in quincunx; reverse rounded, 

 smooth, or finely striated. 



Synocladia, King. — Corallum cup-shaped, with 

 a small central root-like base, reticulated, composed 

 of rounded, narrow, often branched interstices, bear- 

 ing on the inner face from 3 to 5 alternating 

 longitudinal rows of prominent edged pores ; sepa- 

 rated by narrow keels, studded with small, irregular 

 vesicles, alternating with the cell-pores ; dissepiment 

 thin, forming short spur-shaped pinnce, extending 

 upwards from the sides and meeting those from the 

 adjoining interstices at an angle directly upwards, 

 bearing two alternate rows of cell-pores. 



Much of the above information is culled from various 

 sources ; from books, as I said before, too often out 



"Mem. of Geo. Survey, Scotland." E.xplan. of Sheet 23. 



of the reach of the ordinary reader ; and from com- 

 munications by letter from friends and well-wishers. 

 My thanks are especially given to the Rev. W. 

 Howchin, of Haltwhistle, and to Professor Duncan, 

 for the kind assistance they have given me in my 

 researches among the Carboniferous Polyzoa. 1 shall 

 still be thankful for all the information I can obtain 

 from the various sources of rocks or books which can 

 help to throw light on a most important branch of 

 PalKontological history ; and, though writing espe- 

 cially in the interest of working men, who, like 

 myself, can only give to the studies the moments of 

 relaxation between the hours of labour, I hope this 

 rhwne will be profitable to others of more leisure and 

 greater opportunities for study. 

 Atterdiffc, Sheffield. 



( To he continued. ) 



CANADIAN PHLOGOPITE. 



THIS mineral, a variety of mica found in Canada, 

 has the property of so diffracting light that if a 

 small flame be viewed through a thin film of it held 

 close to the eye, a well-defined six or twelve-rayed 

 star is seen surrounding the luminous centre. On 

 rotating the film the rays revolve also. 



Having lately, through the kindness of my friend 

 Professor Rudler, obtained a specimen, I thought 

 that a short account of the constitution and mode of 

 action of this peculiar mineral might, perhaps, be of 

 interest to your readers. 



When a thin film is examined under the inch- 

 power of the microscope, it is seen to be thickly 

 studded with minute crystals ; some short and com- 

 paratively broad, others long and very slender. 

 These are arranged at no definite interval from one 

 another, and are seemingly placed at all angles one 

 with another. But, on careful inspection and com- 

 parison, aided by the quarter-inch power, it is seen 

 that the vast majority of the crystals have their long 

 sides pointing (in the twelve-rayed specimen) in six 

 directions only. These lines of direction make equal 

 angles with one another, so that if produced so as to 

 intersect, a twelve-rayed star would be formed. The 

 confused appearance of the crystals is shown in 

 fig. 103, drawn with the camera lucida. 



If the direction of the crystals in Fig. 103 be traced 

 out', it will be found that (with two exceptions only) 

 they unite to form a twelve-rayed star, with equal 

 angles between the rays. This is shown also in 

 fig. 104, taken at random from another part of the 

 same specimen. Here the crystals are less crowded 

 together, and it may be seen that it needs only one 

 differently-inclined crystal to complete the twelve rays. 

 O^ course in so minute a part it is not strange that 

 one direction should be missing ; all around may be 

 found plenty of crystals pointing in this before-un- 

 represented direction. The variety of Phlogopite 



