SCIENTIFIC SUMMARY. 
277 
led to indicate three primary divisions of the Chelonian order — viz. 1. Aspi~ 
dochelyidce, in which the bony carapace is covered with symmetrical horny 
scutes, including Turtles, Emydians and Tortoises ; 2. Peltochelyidce, in which 
the bony carapace has a granular surface-structure, and is covered with an 
undivided dermis without scutes, including only the Trionychidse ; and 3. 
the Dermatochelyidce , in which the carapace is not developed, but is func- 
tionally represented by a bony skeleton within the skin, as in Sphargis and 
Psephophorus. 
Bohemian Geology. — Mr. J. E. Marr, in a paper read before the Geolo- 
gical Society, has given the results of his investigations of the older Palaeozoic 
rocks of Bohemia, and they are of especial interest, especially in regard to 
the peculiar theory of colonies put forward by the great Bohemian geologist, 
M. Barrande. Mr. Marr commenced with a brief notice of the Pre- 
Cambrian rocks, which are gneisses and schistose limestones with intrusive 
eclogite ; over these lie unconformably green grits, ashes, breccias, horn- 
stones (etage A of Barrande), which the author considers to represent the 
Harlech Group of Wales. Etage B is unconformable with this, but con- 
formable with C, which contains the ‘ primordial ’ fauna of Barrande ; I) con- 
tains the colonies. E to H are Silurian, and more calcareous than those 
underlying them. The base of the group is unconformable with those 
beneath. The following are the associated igneous rocks : — Granite, Quartz- 
felsite, Porphyrite, Mica-trap, Diabase, Diorite, Eclogite. The author made 
a comparison of the various strata with English deposits. The Pre-cambrian 
series much resemble the Diametian and Pebidian of Wales, the latter being 
etage A ; etage B, the Harlech ; etage C, the Menevian, probably a deep-water 
deposit, as is indicated by the abnormal size of the eyes of its Trilobites ; the 
lowest bed of etage D probably represents part of the Lingula Flags of Britain. 
D a, 1, /3 seems to represent the Tremadoc Shale of. Britain, and, like it, 
contains pisolitic iron-ore. Representatives also of the Arenig and Bala beds 
are found. A slight unconformity marks the base or the Silurian. Three 
Graptolitic zones occur. The lowest, or JDiplograptus zone, identical with the 
Birkhill Shales, contains thirteen species of Graptolites ; the next, or Priodon 
zone (four species), resembles the Brathay Flags ; the upper, or Colonies zone 
(five species), resembling the Upper Coldwell Beds of the Lake-district. 
Above these follow representatives of Wenlock, Ludlow, and probably of 
the Passage beds. The author, with the evidence of these, discussed the 
‘ colonies ’ theory of M. Barrande, pointing to the non-intermixture of species, 
notwithstanding the irregular repetition of the zones, the non-occurrence of 
these colony-species in intermediate beds, and other reasons. The strati- 
graphy and palaeontology of several of these colonies was discussed in detail, 
showing it to be probable that their apparent intercalation with later faunas 
is due to repetition by faulting. 
MINERALOGY. 
The Emmet County Meteorite . — This curious meteorite fell near Esther- 
ville, Emmet County, Iowa, lat. 43° 80' N., long. 94° 50' W., within that region 
of the United States which has been remarkable for falls of meteorites, three 
