HARDWICKE'S SCIENCE- GOSSIP. 



237 



extent, which no rock-resistance has been found to 

 fill yet. Between basalt and granite come all the 

 other rocks examined, including a number of lime- 

 stones and sandstones of different varieties. By 

 means of a tabulated scale, it will be possible to 

 estimate the equivalent thickness of any stratum (so 

 far as its conductivity is concerned) by reducing it 

 to that of some standard rock, such as granite. 



The Braixs of Tertiary Mammals.— Profes- 

 sor Marsh, who has been investigating the fossil 

 mammals of the tertiary strata in the Rocky Moun- 

 tain region, with reference to the relative sizes of 

 brain, has arrived at some interesting conclusions. 

 He states that the Eocene mammals all appear to 

 have had small brains, and in some of them the 

 brain-cavity was hardly more capacious than in the 

 higher reptiles. The largest Eocene mammals are 

 the Dinocerata, which were but little inferior to the 

 elephant in bulk. In Dinoceras, Marsh, the type 

 genus, the brain is not more than one-eighth the 

 average size of that in existing rhinoceroses. In 

 the other genera of this order, Tinoceras, Marsh, and 

 Vnitatlieriuvi, Leidy, the smallness of the brain was 

 quite as remarkable. The gigantic mammals of the 

 American Miocene are the Broiitotherium, Marsh, 

 the only genus of the family in which the skull is 

 known ; the brain-cavity is very much larger than 

 in the Eocene Dinoceras, being about the size of the 

 brain in the Indian rhinoceros. In the Pliocene 

 strata of the West, a species of mastodon is the 

 largest mammal, and although but little superior in 

 absolute size to Brontotherium, it had a very much 

 larger brain, but not equal to that of existing pro- 

 boscidians. The tapiroid ungulates of the Eocene 

 had small brain-cavities, much smaller than their 

 allies the Miocene Rhinocerotidaj. The Pliocene 

 representatives of the latter group had well-de- 

 veloped brains, but proportionately smaller than 

 living species. A similar progression in brain- 

 capacity seems to be well marked in the equine 

 mammals, especially from the Eocene OroJuppus, 

 through Mioliippus MAAnchitheritcm of the Miocene^ 

 FUohippus and Hipparion of the Pliocene, to the 

 recent Equus. In other groups of mammals, like- 

 wise, so far as observed, the size of the brain shows 

 a corresponding increase in the successive sub- 

 divisions of the tertiary. These facts have a very 

 important bearing on the evolution of mammals, 

 and open an interesting field for further investi- 

 gation. 



The Iguanadox, a Marsuhal Animal!— At 

 the recent meeting of the British Association, 

 Mr. Waterhouse Hawkins, F.L.S., P.G.S., made 

 some observations, with graphic illustrations, on a 

 pair of symmetrical bones present with the fossil 

 remains of Iguauadon in the well-known slab from 

 Maidstone, now in the British Museum, and com- 



pared those bones with their analogue, as found with 

 a portion of the fossilized skeleton of Hadrosaiirus 

 Foulkii, in the marl beds of the Cretaceous forma- 

 tion at Haddonfield, in New Jersey, North America. 

 The bones in question had been described by Pro- 

 fessor Owen and others as clavicles ; but Mr. 

 Hawkins, in making his restorations for the park of 

 the Crystal Palace, was unable, owing to the great 

 length of the bones, to make room for them in his 

 Iguanadon, and therefore he had to abandon them, 

 and make his model in such a manner as would be 

 consistent with the animal being able to walk. A 

 subsequent comparison of the bones with those of 

 the American analogue led to the conclusion that 

 they were abdominal, and the situation which Mr. 

 Hawkins thought they occupied suggested the pos- 

 sibility of the Iguanadon being a marsupial animal. 



The Classifications of the Labyrintho- 

 dants.— One of the most important papers read in 

 the Geological section of the recent British Associa- 

 tion meeting, was by Mr. L. C. Miall, F.G.S. The 

 following points in the characteristics of the laby- 

 rinthodants were fully noted, as they differ from the 

 statements usually published in ordinary manuals. 

 The skull may be regarded as an amphibian skull, 

 overlaid by crocodilian plates. The teeth occur on 

 the palate and maxillary in double rpws, and are 

 very numerous. Three thoracic plates are present, 

 and the body is covered with bony scutes. They 

 were all, except two genera, provided with four 

 limbs, which may have been penta- or tetra- 

 dactyle. The vertebra; are numerous, and the tail 

 is long, and, in some genera, makes a most efiicient 

 swimming organ. Forty-two genera and 126 species 

 are now known, principally owing to the exertions 

 of recent explorers. Some of these animals, in their 

 mode of life, appear to have been fish -like. Some 

 resembled serpents, others crocodiles, whilst those 

 of Kilkenny appear to have been salamanders. Mr. 

 Miall furnished a tabular view of the classification 

 of the labyrinthodonta, which was divided into ten 

 sections. 



Guide to Belfast. — The members of the 

 British Association this year had their visit ren- 

 dei'cd more interesting than usual by the publi- 

 cation of a " Guide to Belfast " and the adjacent 

 counties, which had been drawn up for the pur- 

 pose by members of the Belfast Field Naturalists' 

 Club. It was an excellent opportunity for the 

 latter to display their intimate acquaintance with 

 their district, and their efforts were thoroughly 

 successful. The " Guide " is a model of what may 

 be produced by a loving, competent; industry. The 

 geology, zoology, botany, archajology, &c., of this 

 wonderful country are fully and accurately drawn 

 up, the illustrations are numerous and graphic, and 

 the industry of the Club was only equalled by its 



