418 Notices of Memoirs — A. M. Heron — Baluchistan Earthquake. 



Out of a total of 101 species, twenty-four have a shell-layer of 

 aragonite — 



Gasteropoda . . .10 (inner and only layer). 



Lamellibranchiata . . 10 (inner of two layers). 

 Cephalopoda ... 4 (outer of two layers) . 



24 



In none of the Cephalopoda recorded above is a third or ' black laver ' 

 present, but an example of Nautilus striatus, Sow., from the Lias is 

 contained in the same collection possessing this in a very good state of 

 preservation. In Baculites an extraordinary thick shell exhibits three 

 distinct layers all of calcite, but the middle one was originally 

 aragonite like other Cephalopods. Of the Cephalopods with an 

 aragonite layer one is a Middle Lias and three are Upper Lias forms. 

 Amongst the Gasteropods which still retain an aragonite layer eight, 

 come from the Lower Lias and all but one from the same locality, 

 Old Dalby, whilst two are Coralline Crag species. The proportion of 

 casts in this group is much larger than in Lamellibranchiata or 

 Cephalopoda. There is, moreover, apparently a geographical limit to 

 the persistence of aragonite in the same formation, as illustrated by 

 the Old Dalby species. There is no restriction of it to certain generic 

 types, though it is found most often in the genera Amberleya, Trochm, 

 Chemnitzia, Cerithium, and Turritella, and amongst these in Trochus 

 and Cerithium especially, though here allied species are not uniformly 

 preserved as aragonite now. 



Amongst Lamellibranchs two species from the Middle Lias are 

 preserved as aragonite ; five are from the Lower, and one species of 

 each come from the Upper Greensand, Gault, and Thanet Sands 

 respectively. 



In the Lower Lias Nucula, Zeda, Cucullcea, and Area in the Middle 

 Lias appear to be especially associated with an aragonite inner layer. 



Thus, in the main, the contentions advanced by Professor Cole hold 

 good in a second series of observations made by me independently, 

 whilst my original suggestion as to aragonite being still the shell- 

 layer in Middle Lias forms is borne out by additional examples and 

 further strengthened by the abundance of Lower Lias types. 



ITOTICES OIF MEMOIRS. 



The Baluchistan Earthquake of 21st October, 1909. By A. M. 

 Hekon, B.Sc, F.G.S. Itecords, Geological Survejr of India, 

 vol. xli, pp. 22-35, 1911. 



rpHE earthquake (of intensity 9, Bossi-Forel scale) occurred at about 

 J_ 5.12 a.m., in a district from 40 to 50 miles to the north of 

 Jacobabad, and resulted in the loss of 231 lives and much damage 

 to the villages of Bagh, Bellpat, and Shahpur. As in most strong 

 earthquakes, the onset of the shock was sudden. Mr. Heron traces 

 three isoseismal lines from the evidence of damaged buildings. They 



