84 Reports and Proceedings — Geological Society of London. 



Geological Society of London. 



I.— December 21st, 1904.— J. E. Marr, Sc.D., F.E.S., President, 

 in the Chair. The following communications were read : — 



1. "On certain Genera and Species of Lytoceratidse." By S. S. 

 Buckman, F.G.S. 



This paper deals with certain specimens sent by Mr. Beeby 

 Thompson from the Northampton Sands, one of which is remarkable 

 for its homoeomorphy with Phylloceras. In order to classify the series 

 of Toarcian-Aalenian Lytoceratidee to which these species belong 

 (jurense and allied groups), it is necessary to note that there is 

 evidence of a definite sequence of phylogenetic stages. In orna- 

 ment there is, at first, elaboration ; but, later, simplification from 

 a costate to a smooth stage. In whorl-shape there is a tendency to 

 pass from the primitive evolute to the involute whorl, the umbilicus 

 constantly contracting. Parallel with this there is a further 

 tendency to pass from stout to more compressed whorls. While 

 the Lytoceratidae have a more primitive whorl-shape than the 

 Phylloceratidge, their lobe-line is more advanced ; and hence, while 

 the advance of the former produces a certain external homoeomorphy 

 with the latter, the more advanced lobe-line remains a feature of 

 distinction. The successive stages of development may be indicated 

 in terms of species, thus : (1) Germaini, (2) torulosum, (3) annulose 

 species not yet named, (4) jurense, and (5) phylloceratoidan. Four 

 new genera are described and two new species ; three new names 

 are proposed, and one generic name revised. 



2. " The Leicester Earthquakes of August 4th, 1893, and 

 June 21st, 1904." By Charles Davison, Sc.D, F.G.S. 



The earthquake of 1893 was a twin, with its principal epicentre 

 between Markfield and Woodhouse Eaves, and the other near Tugby, 

 about 17 miles to E, 34° S. Its disturbed area contains about 

 2,200 square miles. In the north-western focus, the originating 

 fault hades to the north-east, and is probably one of the group of 

 faults on the north-east side of the Charnwood anticlinal axis, which 

 appear to hade in the direction given. In the south-eastern focus, 

 the fault hades in the opposite direction, the change of hade taking 

 place a short distance to the south-east of Leicester. 



On June 21st, 1904, two shocks were felt : the first a very slight 

 one, at about 3.30 a.m. ; the second at 5.28 a.m. The epicentre 

 of the earlier shock was in the neighbourhood of Markfield and 

 Groby, or near the south-eastern margin of the north-western 

 focus of 1893. The second shock disturbed an area of about 

 1,200 square miles, and was a double shock, not a twin, for the foci 

 were overlapping. It originated in a fault running nearly north- 

 west and south-east, hading to the south-west, and passing a short 

 distance from Tugby, and therefore in all probability coincident with 



