438 Scientific Intelligence. 



his studies include specimens in which stem and petiole are or- 

 ganically united, thus rendering more conclusive the proof that 

 lyginodendron Oldhamium is a true fern, probably belonging to 

 the Spheftopterids, and that the stems of some, at least, of the 

 Carboniferous ferns "developed their xylene or vascular structure 

 exogenously through the instrumentality of a meristemic zone of 

 the innermost cortex, which practically must be regarded as a 

 cambium layer." d. av. 



1 1 . Catalogue of the Fossil Cephalopoda in the British Museum, 

 Part II; by Arthur H. Foord. — Although nominally a cata- 

 logue, this work possesses the nature of a monograph, and is a 

 positive contribution to the literature of the subject. A full 

 bibliographical notice is given of each genus and species, together 

 with detailed descriptions of the principal characters. The pres- 

 ent volume includes the families Lituitidse, Trochoceratidae, and 

 Nautilidse. The text is enriched with numerous wood-cuts drawn 

 by the author. c. e. b. 



12. Mineralogical notes, by W. E. Hidden and J. B. Mackintosh. 

 (Communicated). Auerlite. — The lemon-yellow variety found on 

 Price's Laud in Henderson County, N". C, has proved to contain 

 more P 2 5 and correspondingly less Si0 2 than that from the 

 Freeman Zircon Mine, three miles northeasterly in the same 

 county. The density varies between 4*051 and 4*075. The ratio 

 of P„0 5 + Si0 2 : H 2 is the same as is demanded by the formula 

 deduced from the former analyses. It is to be noted that the 

 density decreases as the percentage of phosphoric acid increases. 

 Among the crystals we have observed twins parallel to 1-i, as in 

 zircon, rutile and cassiterite. The analysis has given : 



•590 = 1 





Molecular Ratio 



P.O. 



8*58 X T f p 3(32 



Si0 2 



6*84 X -fa -228 



Th0 2 



[72*16] X^U ' 553 



Fe 2 3 



1-78 X yfjj- -<)33 



H,0 



10-64 X A 1-182 



X2 1*172 = 2 



=2 



100-00 



The thoria was tested and found to be quite pure but was 

 unfortunately lost before it could be weighed. The percentage 

 above given is determined by difference. The above analysis 

 confirms the formula previously assigned by us to this mineral 



(see this Jour., Dec. 1888, p. 462) i. e.,— Th0 2 , j ^>°g I 2H 2 



or a thorite (orangite) in which part of the silica is replaced by 

 its equivalent in phosphoric acid, when 3Si0 2 = 1P 2 5 . The 

 P 2 5 tends to be in excess. 



Sulphohalite [Na 2 (fS0 4 , J-Cl)]. — A careful examination of the 

 few crystals available has proved an apparent tendency to hemihe- 

 drism, the octahedral faces being present only on the alternate 

 trihedral solid angles of the dodecahedron. This, if confirmed, 



