60 Rev. 0. Fisher — Formation of Mountains. 



gemmation is S. sub-ccespitosum ; but this is a very much smaller 

 form, and is solitary in its habits. Detached individuals of ^. pro- 

 liferum, in which budding appears not to have taken place, may 

 usually be recognized by their great length and almost cylindrical 

 form, there being little or no increase of diameter as the calice is 

 approached. There are also usually regularly developed constric- 

 tions and swellings of growth. 



Locality and Formation. — Extraordinarily abundant in one bed of 

 the Corniferous Limestone at Ridgeway. 



EXPLANATION OP PLATE IV. 



Fig. 5. — a. Fragment of Alveolites cryptodens, Billings. h. Alveolites labiosa; Billings. 



c. Portion of the stem of Alveolites conferta; Moliolscai. All of the natural size. 



From the Corniferous Limestone. 

 Fig, 6. — a. Fragment of Alveolites ramulosa, Nich., natural size. b. Portion of the same 



magnified, e. Fragment of Alveolites Billingsi, Nich., natural size. From the 



Corniferous Limestone. 

 Fig. 7. — a. Fragment of Chaetetes moniliformis, Wich., en\?ir%e6.. 6. A portion of the surface 



of the same still further enlarged, c. A portion of the surface of Chaetetes Bar- 



randi, Nich., greatly enlarged. From the Hamilton Group. 

 Fig. 8. — ra. Portion of the crust of Chaetetes quadrangular is, Nich., encrusting Heliophyllum 



Halli, slightly enlarged. 6. A few of the calices of the same greatly enlarged. 



From the- Hamilton Group. 

 Fig. 9, — Heliophyllum suh-cmspitosum, Nich., of the natural size. From the Hamilton Group. 



(To he continued.) 



IV. — On the Formation of Mountains viewed in Connexion 



WITH the Secit£Ar Cooling of the Eakth. 



By the Eev. 0. Fishek, M.A., F.G.S. 



Being- the substance of a paper read at Cambridge, December 1, 1873. 



AS a further contribution to the subject of mountain elevation, of 

 which the Editor of the Magazine has given an interesting 

 and lucid resume in his late Presidential Address to the Geologists' 

 Association, 1 I send an outline of a paper which was read by me in 

 December before the Cambridge Philosophical Society. 



The subject required to be treated in too technical a manner to 

 appear in full in the Magazine, or I should have chosen that as the 

 .vehicle for its publication ; for it was in truth a continuation of a 

 paper which has already appeared in these pages .'^ 



1. 



Eeferring to that paper for the explanation of the meaning of the 

 1 See Geol. Mag. 1873, Vol. X. p. 530. 2 Vol. X. p. 248. 



