Bevieios — T. Mellard Reach — On Mountain Ranges. 229 



transverse tabulse are present, as well as the vertical lamellae, whilst 

 ill the latter, the transverse structures are irregular. Associated with 

 the ordinary forms of Archcsocyathus, a peculiar fossil, consisting of 

 anastomosing, apparently homogeneous fibres, frequently occurs. It 

 is believed by the author to be the vegetative state of development 

 from which the complete cups of ArcTiceoeyathus originate, and thus 

 to indicate a true alternation of generations in these Cambrian fossils ! 

 To this form, though not regarded as an independent genus, the name 

 Protopharetra is given. 



An equally surprising statement is, that delicate threads or fibres 

 of calcite present in the interspaces of the walls of some examples 

 of Arcliceocyatlnis and Coscinocyathns are the fossilized remains of 

 such soft organic structures as sarcode- threads, muscle-fibres and 

 tentacles. The author thinks it possible that these structures may 

 have been inclosed by the ooze, and then replaced by calcite ! 



Though the author has described in detail numerous species, it can 

 hardly be said that our knowledge of the true nature and affinities of 

 ArchcBocynthus and its allies has been increased. The author doubts 

 the correctness of the observation of Billings as to the spicular 

 nature of the walls of Archceocyathus, and thinks that the spicules 

 figured were accidental intrusions. 



Though we regret our inability to accept most of the determinations 

 and conclusions of the author, we nevertheless readily admit the 

 value of the work which he has done in bringing to light and 

 describing the organisms in these unpromising Cambrian rocks of 

 Sardinia. It is of great interest to know that many of the forms ai'e 

 closely similar to those recorded by Billings from the so-called 

 Calciferous rocks of the Mingan Islands and other localities bordering 

 the St. Lawrence, and this similarity will probably be further shown 

 when the Trilobites and other fossils are described. It may also be 

 mentioned that this work has a direct bearing on questions connected 

 with British geology, since Archceocyathus has lately been discovered 

 by members of the Geological Survey of Scotland in the Durness 

 limestones. The specimens, though not uncommon, are but frag- 

 mentary and in a poor state of preservation ; but, in spite of this, 

 Mr. B. N. Peach, F.G.S., has been able to ascertain from them some 

 important conclusions respecting the relations of Archcsocyathiis to 

 C'aluthium, Bilk, which it is hoped will soon be published. 



Q. J. HlNDE. 



II. — The Origin of Mountain Eanges. By T. Mellakd 

 Eeade, C.E., F.G.S., F.R.I.B.A. (London, Taylor & Francis, 

 1886.) 



THIS is a handsome octavo volume of 359 pages, profusely illus- 

 trated with forty-two full-page or folding lithographic plates. 

 The short final chapter contains the author's main conclusions ; 

 and these are further condensed into its first two sentences. 

 " Mountain-ranges are ridgings-up of the Earth's crust, which take 

 place only in areas of great sedimentation. The exciting cause of 

 the various horizontal and vertical strains, ending in the birth of a 



