January 25. 1900] 



NATURE 



291 



kius of irreversible heat-phenomena from probability 

 considerations becomes more and more difficult the more 

 it is studied. But physicists have given us another source 

 of irreversibility, of which the kinetic theorist has hitherto 

 made little use. The equation 



representing propagation of spherical waves is satisfied 

 mathematically by r^ = F^i;/ + r) +/(«/- r) ; but the 

 physicist has to make the axiom that waves always radiate 

 from, and never converge to a source of disturbance, and 

 hence, that the second term alone exists in nature. Seeing 

 that the molecules on our earth derive so much of their 

 heat-energy from the sun, which energy is (if we may use 

 the expression) transported across some ninety million 

 miles of ether by equations of this type, it is surely de- 

 sirable that some working hypothesis should be formu- 

 lated for the conversion of radiant energy into energy of 

 heat motion, and a kinetic theory involving such a hypo- 

 thesis would explain irreversibilityasanatural consequence 

 of the simple axiom involved in the suppression of 



We trust that neither Mr. Burbury nor Prof Boltzmann 

 \\ ill construe any of these remarks into expressions of 

 criticism on the points of difference between their con- 

 clusions, and we hope that ere long both these writers 

 \\ ill enlighten us further on the questions at issue. The 

 writer of the present review has (doubtless in common 

 with many others) spent a considerable amount of time 

 in trying to attack that tantalising question of tempera- 

 ture from a kinetic standpoint coupled with probability 

 considerations, or even deducing the law of molecular 

 distribution from the temperature-property ; but every 

 attempt leads to an impenetrable wall built of dense 

 assemblages of molecules which cannot be assumed to 

 follow the Boltzmann-Maxwell distribution, and which 

 seem to say to the mathematician, " Thus far shalt thou 

 yo, but no further." G. H. Bry.\n. 



THE ZOOLOGY OF THE INDIAN SEAS. 



A Descriptive Catalogue of the Indian Deep- Sea Fishes 

 tn the Indian Museum. Pp. iii-f-212 and viii. 



An Account of the Deep-Sea Brachyura. Being Systematic 

 Reports upon the Materials collected by the Royal 

 Indian Marine Survey Ship '■'"Investigator" 1874- 

 1899. By A. Alcock, M.B. Pp. ii-i-85. (Calcutta: 

 Printed by the Trustees of the Indian Museum, 1899.) 



THE Catalogue of Deep-Sea Fishes is a monumental 

 work, since it completes the description in full of 

 a large number of species already listed in the author's 

 papers, now well known, and illustrated in the " Illus- 

 trations of the Zoology of the Investigator" which he 

 inaugurated in 1892, and which, thanks to the skill of his 

 native artists, is likely to become classic. 



The fishes dealt with number 169 species, the Ana- 

 canthini and Physostomi being, as might be expected, in 

 the majority, and but two of them Plectognathi. 126 of 

 these stand to the record of the Investigator alone, and 

 43 only appear identical with species found elsewhere ; 

 23 are said to be common to the Indian seas and the 

 Atlantic, and a special feature is the occurrence of a 

 NO. 1578, VOL. 61] 



Trachinoid fish (a Bembrops) originally found in Japan- 

 Dr. Gunther, as is pointed out, has already familiarised 

 us with the idea of a former open connection between 

 the Mediterranean and Japanese seas ; and, discussing 

 this fish and certain related forms, the author dismissing 

 the " comfortable formula " " similarity of conditions," 

 is led to the conclusion that " a considerable part of the 

 fish-fauna of the Oriental region originated from, and to 

 a certain extent is a remnant of, the fauna of the Tertiary 

 Mediterranean of Suess — of a Mediterranean that ex- 

 tended from the present Gulf of Mexico, through the 

 present Mediterranean basin, far into the eastern hemi- 

 sphere." 



The chief novelty of the present work is a chart com- 

 piled from Koken's "Vorwelt und ihre Entwickelungs- 

 geschichte " with the object of rendering clear the 

 bearings of the above conclusion. The present coast-lines 

 and those supposed to have existed during the Tertiary 

 period are indicated in dissimilar contours, and the pre- 

 sumed area of the Inland Sea is rendered appropriately 

 clear. In the construction of this chart the author has 

 sought the advice by Mr. T. H. Holland, formerly of the 

 Royal College of Science, London, and that gentleman's 

 splendid work on the Geological Survey of India amply 

 justifies the choice. 



The fresh-water fishes (mainly OstariophysecC and 

 Cichlidas) come in for consideration. The occurrence of 

 a Symbranchid species common in Tropical America and 

 Australia, of Cyprinodonts known from Tropical Africa 

 and America, are duly emphasised, while the author's 

 records concerning the Cichlidae (Chromides) have an 

 especial value now that our knowledge of this remarkable 

 group is being revolutionised by oar distinguished 

 English Ichthyologist, Boulenger. 



It is praise sufficient to remark that this grand mono- 

 graph in no way falls short of its predecessors we have 

 so recently reviewed (see Nature, vol. Ix. p. 459), and 

 that it will remain for generations a standard work of 

 reference. 



The report on the Brachyura is serial with those on 

 the Madreporaria and Ophiuroidea, and, like the former, 

 is prefaced by an account of the history of the 

 expedition and of its association with the Indian 

 Museum. It completes the work of the expedition on 

 the crabs, and as regarding descriptions of new species it 

 is supplemental to a series of earlier papers by the 

 author, his former associate and predecessor in office, 

 the late Prof Wood-Mason, and his present colleague. Dr. 

 A. R. L. Anderson, extending over a period of more than 

 twenty years. The present volume deals with 53 species 

 and 38 genera, with two exceptions from depths of over 

 100 fathoms ; and of these 21 genera and 5 species are 

 known from other seas. Interest centres m the dis- 

 covery of afifinities between the fauna of the Indian and 

 Atlantic deep-sea areas, which the author is disposed to 

 interpret as indicative of a former open connection 

 between the two, for which he has already argued in re- 

 porting upon the Madreporaria. Bathymetrically one 

 species only (an Ethusa) was obtained at a depth ex- 

 ceeding 1000 fathoms, 3 {Ethusa, 2 sp. and a Hyp- 

 sophrys) between 800 and 1000 fathoms, 3 between 

 500 and 800, and 18 between 400 and 500, while of the 

 majority obtained at depths of from 100 to 400 fathoms 



