Sune 8, 1871 | 
NATURE 
115 

SOCIETIES AND ACADEMIES 
LONDON 
“ Geological Society, May 24.—Prof. John Morris, Vice- 
President, inthe chair. Messrs. Mosley, Colvin, Noble, F,R.A.S., 
and Davey, were elected Fellows of the Society. The following 
communications were read :—(1) ‘‘On the principal Features of 
the Stratigraphical Distribution of the British Fossil Lamelli- 
branchiata.” By Mr. J. Logan Lobley, F.G.S. In this paper 
the author showed, by means of diagrammatic tables, what 
appears to be the present state of our knowledge of the general 
stratigraphical distribution of the fossil Lamellibranchiata in 
Britain. As a class, the Lamellibranchs are sparingly repre- 
sented in the Lower, and more numerously in the Upper Silurian 
group, and fall offagain in the Devonian ; they greatly increase in 
number in the Carboniferous, become scanty in the Permian and 
Trias, and attain their maximum development in the Jurassic 
rocks. They are also largely represented in the Cretaceous and 
Tertiary series. The stratigraphical distribution of the two great 
subordinate groups, the Siphonida and the Asiphonida, corre- 
sponds generally with that of the class; the Siphonida pre- 
dominate over the Asiphonida in Tertiary formations, whilst the 
reverse is the case from the Cretaceous series downwards. Nearly 
all the families of Lamellibranchs are represented in the Jurassic 
and Carboniferous rocks, and in the former very largely. The 
author remarked especially on the great development of the 
Aviculidz in Carboniferous times. Mr. Etheridge, after notic- 
ing the importance of the paper, remarked that possibly the 
great difference observed in the proportions of Lamellibran- 
chiata in different formations might to some extent be due to our 
want of knowledge. Of late years, in the Caradoc and Lower 
Silurian series, the number of species had been nearly doubled, 
principally through the persevering industry of one single 
observer, Lieut. Edgell. The same was to some extent the case 
in the Carboniferous rocks, owing to the collections of Mr. Car- 
rington. Much was also being done for the Oolitic series, in con- 
nection with which the names of Mr. C. Moore, Mr. Sharp, and 
Dr. Bowerbank ought to be mentioned. Mr. Griffiths and the 
Rey. Mr. Wiltshire were doing the same work for the Gault. 
What the late Mr. S. P. Woodward had done as to the distribu- 
tion of the different species of molluscs through time, Mr. Lobley 
was doing on a larger and more extended scale. Prof. Ramsay 
was glad to find that Mr, Lobley was, to some extent, doing the 
same for the Lamellibranchiata as Mr. Davidson had done for 
the Brachiopoda. He did not know how the case might be with 
the Silurian and Devonian formations, but in the Carboniferous 
strata the Lamellibranchiata were obtaining a preponderance over 
the Brachiopoda, He accounted for their comparative absence 
in formations of other ages, especially between the Upper Silurian 
and Rhietic beds, by the best known areas of those periods having 
been mainly continental, or containing principally freshwater or 
inland sea remains, so that the true marine fauna wasabsent. In 
Carboniferous times possibly the true relative proportions of the 
two forms had been preserved in the deposits. Mr. Judd was 
doubtful as to the safety of placing too great reliance upon figures. 
He questioned whether some of the conclusions as to the great 
increase of Lamellibranchiates between the Carboniferous and 
Jurassic periods could be substantiated. Much depended on the 
amount of the rocks present in different countries, and the study 
bestowed on each. ‘The conditions also for the preservation of 
the fossils might be more favourable at one time than another. 
Mr. Carruthers considered the tables as of the greatest value, as 
indicating the present state of our knowledge. He called attention 
to the difference of conditions under which deposits had accumu- 
lated, which must have to some extent affected the proportion 
of Lamellibranchiates preserved in the different formations. 
Mr. Charlesworth remarked on the occurrence of Zyigonéa in 
the Australian seas, and on there being varieties of form among 
specimens of existing species so great that if they were found 
fossil they might be regarded as of several species. Mr. Hughes 
considered that the data were too incomplete to justify the 
generalisations of some of the previous speakers. It had been 
pointed out that whenever the tables showed a very large num- 
ber of Lamellibranchs from any formation, that formation had 
been carefully worked out by local observers ; and therefore he 
would like to know in each case the proportion the Lamellibran- 
chiata bore to the total number of fossils found. It had been 
shown also that a larger proportion of Brachiopoda had been 
found in the older rocks, and of Lamellibranchiata in the 
newer, But in the older rocks whole genera of Lamelli- 

branchs are confined to horizons and localities which are 
not cut off by stratigraphical breaks, such as would allow us 
to think it atall probable that they can be characterised by 
peculiar genera, He thought the scarceness and irregular 
occurrence of Lamellibranchs in the older rocks could be best 
explained on the supposition that those portions of the older de- 
posits which were least favourable to Lamellibranchs happened to 
be those now chiefly exposed to our search, and that those few 
portions are only in part worked out. Mr. Jenkins observed that 
in thick deposits there was a far greater likelihood of numerous 
forms being present than in thin, for thickness meant time, and 
time meant variation. Prof. Morris dissented from this view, as 
in thin littoral deposits an enormous number of shells might be 
present, while in beds formed of deep sea they might be almost 
entirely absent.—2. ‘‘Geological Observations on British 
Guiana,” by Mr. James G. Sawkins, F.G.S. In this paper the 
author gave a general account of his explorations of the Geology 
of British Guiana when engaged in making the geological survey 
of that colony. He described the rocks met with during excur- 
sions in the Pomeroon district, along the course of the Cuyuni 
and Mazurunirivers, on the Demerara river, on the Essequibo 
and its tributaries, on the Rupununi river, and among the southern 
mountains. The rocks- exposed consist of granites and meta- 
morphic rocks, overlain by a sandstone, which forms high 
mountains in the middle part of the colony, and is fre- 
garded by the author as probably identical, or nearly iden- 
tical, with the sandstone stretching through Venezuela 
and Brazil, and observed by Mr. Darwin in Patagonia. 
Prof, Ramsay remarked upon the barrenness, from a geological 
point of view, of the district investigated by Mr. Sawkins, and 
especially called attention to the absence of fossils in the strati- 
fied rocks. He referred briefly to Mr. Sawkins’s labours in 
Trinidad and Jamaica, and to his discovery of metamorphosed 
Miocene rocks in the latter colony exactly analogous to the 
metamorphic Eocene rocks of the Alps. He was glad to sce 
that the author had brought forward examples of cross-bedding 
in metamorphic rocks, and considered that the results adduced 
were favourable to those views of the metamorphic origin of 
granite which he had himself so long upheld. Mr. D. Forbes, 
on the contrary, considered that the facts brought forward by Mr. 
Sawkins were confirmatory of the eruptive nature of the granites 
observed, He added that cross-bedding was common in igneous 
rocks and eyen inlavas, Mr. Tate remarked that in the country 
to the north of the district described in the paper metamorphic 
rocks abound. He considered that the series of metamorphosed 
Jurassic rocks extends across the whole north of South America, 
and perhaps into California. Similar sandstones to those de~ 
scribed occur in the basin of the Orinoco, and contain fossils which 
show them to be of Miocene age. Mr. Tate did not consider these 
sandstones as the equivalent of the Patagonian sandstones, as 
from the shells contained in the latter they would appear to be 
Pliocene or Pleistocene. Mr. Sawkins, in reply to a question 
from Mr. Tate, stated that the only gold found in the country 
had probably been carried down from the well-known gold dis- 
trict of Upata. He also entered intoa few additional details 
connected with the chief points in his paper, dwelling especially 
upon the physical features of the country, in ilustration of which 
several landscape drawings were exhibited. 
Royal Institution of Great Britain, June 5.—Sir Frederick 
Pollock, Bart., M.A., vice-president, in the chair, Silas Kem- 
ball Cook, Miss Elinor Martin, Dr. Charles Bland Radcliffe, 
and Mrs, Radcliffe were elected members of the Royal Institu- 
tion. The special thanks of the members were returned for 
the following donation to ‘‘The Fund for the Promotion of 
Experimental Researches” :—Sir Henry Holland, Bart. (thir- 
teenth annual donation), 40/, 
Anthropological Institute, May 29.—Prof. Busk, F.R-S., 
vice-president, in the chair. George Latimer of Puerto Rico 
was elected a member. Mr. F. G. H. Price read a paper ‘‘ On 
the (Quissama Tribe of Angola,” inhabiting that portion of An- 
gola situated on the south bank of the Quanza river. The 
country had lately been visited by Mr. Charles Hamilton, 
well known for his travels among the Kaffirs. The Quissama 
bear the reputation of being cannibals, but cannibalism, although 
undoubtedly practised by them to some extent, does not largely 
prevail. The men are well formed, and average about five feet 
eight inches in height, they are copper-coloured, have long, coarse, 
and in some instances, frizzled, hair; their heads are mostly well 
developed, and the Roman nose is not unfrequently met with, 
