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POPULAR SCIENCE REVIEW. 
bottom, and partly from such as have subsided to the bottom only after 
death, goes to build up the calcareous stratum ; nearly the whole of the 
silica, whether derived from the deep-sea sponges or from surface Protozoa, 
goes to form the flints. 4. That the sponges are the only really important 
contributors to the flint-formation that live and die at the sea-bed. 5. That 
the flints are just as much an organic product as the Chalk itself. 6. That 
the stratification of the flint is the immediate result of all sessile Protozoan 
life being confined to the superficial layer of the muddy deposits. 7, That 
the substance which received the name of 1 Bathybius ,’ and was declared to 
be an independent living Moneron, is, in reality, sponge-protoplasm. 8. 
That no valid lithological distinction exists between the Chalk and the 
calcareous mud of the Atlantic; and pro tanto, therefore, the calcareous 
mud may be, and in all probability is , 1 a continuation of the Chalk-formation.’ 
Bohemian Permian Amphibia. — A well-known Bohemian palaeontologist, 
Dr. Anton Fritsch, has commenced the publication of a monograph on the 
fauna of the coal and limestone of Permian age, occurring in Bohemia. A 
most interesting assemblage of fossils has been discovered in these rocks 
within the last ten years. It includes, at present, about forty-three species 
of amphibians, thirty-three fishes, eleven arthropods, and an Anthracosia, and 
many of the forms are exceedingly remarkable. They are being described in 
detail and admirably figured by Dr. Fritsch, in the work Fauna der Gaskohle 
und der Kalksteine der Permformation Bohmens, the first part of which has 
quite recently appeared. In this the author gives an account of the geo- 
logical formation from which the remains described have been obtained, 
and other general information connected with the fossils, and then describes 
the species of Amphibia, preceding his descriptions with some generalities 
upon the group to which they belong. He refers all the forms noticed in 
his first part to Cope’s Order Stegocephali, which comprises the Labyrintho- 
dontia, Ganocephala, and Microsauria of other writers, and places them 
under four genera, namely, Branchiosaurus, Sparodus, Hylonomus, and 
Duwsonia. 
Branchiosaurus resembles the Earth-salamanders in possessing gills, and 
the author remarks that in their broad rounded head, short thick body, well 
developed limbs, terminating in digits, and their rudder-like tails, they sug- 
gest comparison with larval forms of the existing Urodela. Branchiosaurus 
salamandroides attained a length of two and a half inches ; its skeleton was 
ossified early in life, the bones being completely defined in specimens only a 
quarter of this length. The skin was dense and its impression is preserved 
in most of the specimens ; when highly magnified, ridges are seen upon it, 
constituting the first indications of scales, which become more developed on 
the lower surface of the body. The general form of the head is nearly 
semicircular ; the maxillaries and premaxillaries carry numerous short pointed 
teeth ; the orbits are rather large, and in well-preserved examples show a 
circle of about fourteen sclerotic bones ; the lower jaw is attenuated in front, 
composed of three elements, — articular, angular, and dentary, the latter having 
about twenty teeth ; and on each side of the hinder part of the skull there are 
two branchial arches, which bear two rows of small, spheroidal bones, each 
furnished with a curved spine. The trunk vertebrae are about twenty in 
number, and all except the first bear ribs. The sacrum consists of a single 
