190 



HARDWICKE'S SCIENCE-GOSSIP. 



which a detachment from the Geological Survey took 

 the field in Sutherlandshire, Dr. Hicks, Dr. Callaway, 

 and Professor Lapworth had all thrown light upon 

 the subject ; while Dr. Geikie was prevented, by want 

 of space, in his paper which appeared in the following 

 year in " Nature," from indicating the share which 

 previous writers had had in producing the result. 



Cone-in-cone Structure. — In a paper read 

 before the Geological Society of Glasgow in March, 

 Mr. John Young, F.G.S., described the structures 

 known as Cone-in-cone, and gave an account of results 

 arrived at by him after a careful study of numerous 

 specimens. This structure is found in sedimentary 

 strata of various formations, being, in the Car- 

 boniferous rocks of West Scotland, often associated 

 with beds of clay-carbonate of iron of probable shallow 

 lacustrine deposition. Cone-in-cone consists of a 

 series of cones one within the other, arranged 

 vertically with their apices downwards, the broad 

 ends of the upper cones in the case of the larger 

 examples terminating upon the upper surface of the 

 bed in which they occur. Mr. Young thinks the 

 effect, which had been ascribed by previous observers 

 to various causes, to be due to the upward escape of 

 gases generated in the deposit by the decomposition 

 of organisms present in it. An abstract of his paper, 

 with other conclusions arrived at by him, may be 

 found in the " Geological Magazine " for June. 



Carboniferous Sharks. — A recent issue of the 

 Glasgow Geological Society's Transactions contains 

 an interesting contribution to our knowledge of one 

 of the Carboniferous Selachians, Psephodus magnus, 

 Agass., by Dr. R. H. Traquair, F.R.S. Slowly, yet 

 surely, the progress of palreontological research is 

 tending to reduce the number of provisional names 

 with which the difficult study of fossil relics is 

 necessarily encumbered, and the present paper is one 

 more instalment towards bringing about this very 

 desirable result. After reviewing the work of previous 

 writers on the subject, the author proceeds to describe 

 a remarkable specimen from a shaly bed in the 

 Carboniferous Limestone Series of East Kilbride, 

 Lanarkshire, which not only exhibits two large teeth 

 of the kind named Psephodus magnus, by Agassiz, but 

 also shows forty-four others in intimate association, 

 with portions of the cephalic cartilage and jaws, and 

 the more or less obscure remains of a series of 

 vertebral spinous processes. The dental group, un- 

 doubtedly belonging to a single mouth, comprises 

 forms hitherto referred to no less than three genera 

 and four species, and as the series is evidently in- 

 complete, there may possibly have been more of these 

 provisionally-named types. The two teeth of Agassiz' 

 Psephodus magnus seem to belong respectively to the 

 upper and lower jaws, and would thus imply the 

 deficiency in the present example of at least two other 

 co) responding forms : more than twelve of the smaller 

 teeth are referable to Agassiz' Ilelodus plaints, which 



had been previously identified with Psephodus by 

 Captain Jones ; another is probably Helodus rudis, 

 McCoy ; while the remainder, in advance of those 

 just mentioned, belong to the so-called Lophodus, and 

 were originally designated specifically by Agassiz as 

 L. didymus and L. livvissimits. Helodus and Lopho- 

 dus, therefore, can henceforth have only a " con- 

 ventional existence," and the discovery of this Scotch 

 specimen is an interesting confirmation of what had 

 already been ascertained in regard to an allied genus, 

 Cochliodus, from the Lower Carboniferous of the 

 United States, — namely, the presence of small Helodus- 

 shaped teeth on the symphysial portion of the jaw, iu 

 front of the main crushing plates, exactly as is the 

 case in the living Port Jackson Shark (Cestracion) of 

 the Australian Seas. (See article in these pages last 

 December, Vol. XX. pp. 269-271.) Dr. Traquair's 

 specimen, moreover, indicates that some of the 

 flattened Helodoid forms were placed posteriorly, — 

 again analogous to Cestracion ; but neither the Scotch 

 nor the American examples of Cochliodonts are 

 sufficiently perfect to allow of a complete restoration 

 of the dental armature of the mouth, and it will thus 

 be necessary to remain content with these partial 

 glimpses of the facts until further research has provided 

 more ample materials. — A. S. IV. 



NOTES AND QUERIES. 



Fungoid Disease in Fishes, &c. — In reply to 

 the query of " Hal," p. 166, Science-Gossip, it 

 may be generally insisted that fish in captivity, sooner 

 or later, suffer ; generally from sudden and injudicious 

 changes of water, but even under the best conditions 

 of aeration and the growth of plants they wither. 

 Of the Axolotl (Siren pisciformis), the writer can 

 offer reliable information from actual experience. In 

 a tank holding about five gallons, situated in a cool 

 corner of an ordinary domicile, have lived, for eight 

 or more years, Axolotls. At the present time, the 

 survivor (by right of age, for he cannot be less than 

 ten years old) is perfectly happy, and growing grey 

 in the service of admiration, fed once a week (gene- 

 rally Sunday morning) on strips of beef; the secret 

 of his health and longevity is the outcome of the 

 simple lesson which may be applied to tank manage- 

 ment in general : ?iever change the water ; supply 

 evaporation from good ponds, and regulate as far as 

 possible the balance of animal and vegetable life. 

 Axolotls, under such circumstances, not only escape 

 the ravage of " fungoid growths," but encourage the 

 development of a world of microscopic beauty, seem- 

 ingly keeping the balance of life even. Except when 

 running water or artificial aeration can be secured, 

 fish are not desirable occupants of an aquarium ; at 

 least, they should never be included in a tank devoted 

 to microscopic developments ; and although fish in this 

 sense are foes, it can be confidently and emphati- 

 cally stated that an Axolotl in a tank of prosperous 

 permanence not only encourages, but assists and 

 develops an amount of microscopic life rarely seen 

 under any other circumstances. — E. T. D., Crouch 

 End. 



