Jan. 12, 1888] 



JVA TURE 



243 



alter the descriptions we reach a discussion of this very 

 point, and we find that most of the differences on which 

 emphasis has been placed by other authorities are not 

 found to be constant when a large number of specimens 

 are examined, that the two races pass by gradual tran- 

 sition one into the other, but that as a rule in the southern 

 there are fewer pyloric cxca than in the northern, and 

 that the Sewin usually loses the teeth on the body of the 

 vomer, at an earlier age than the northern sea trout. 



The following are the different forms of non-migratory 

 fresh-water trout which have been distinguished as dis- 

 tinct species, and whose synonymy is given in the present 

 work : Brook trout, Lochleven trout, Crasspuill trout, 

 Estuary trout, Orkney trout, Cornish trout, Great Lake 

 trout, Giilaroo trout, and Swaledale trout. Short de- 

 scriptions of these are given in footnotes, excepting 

 the brook trout and the Lochleven trout, which are 

 discussed at length in the text. These descriptions, 

 though brief, are not diagnostic, and it requires the 

 most careful reading and comparison to find in what 

 respects the varieties differ from one another. Mr. 

 Day believes that there is no definite line to be drawn 

 between anadromous sea trout and non-migratory fresh- 

 water trout, intermediate forms being common ; nor 

 between the different varieties of fresh-water trout. But 

 granting — for we are inclined to agree with Mr. Day's 

 conclusions— that in all these forms we have but one 

 species, it is surely worth while to give a more lucid and 

 more definite account of the differences between them. 

 The arguments which Mr. Day employs to prove that all 

 forms of trout, whether anadromous or confined to fresh 

 water, belong to one species, may be divide'd into three 

 classes, and his book would have been much easier to 

 read if he had kept them separate. The first class are 

 those which show that the various forms graduate into 

 one another, or that the peculiarities of one are included 

 in the range of variation of another ; the second, those 

 which show that removal to a different environment 

 causes the characteristics of one form to be transmuted 

 into those of another ; the third, those which show that 

 the several forms breed freely when crossed. 



All the species of char which have been distinguished 

 in Britain are considered in this book as belonging to one 

 variable species which is identical with the Sal/no salve- 

 linns, Linn., and S. iimbla, Linn , — that is, with the Con- 

 tinental char. A similar criticism may be passed on Mr. 

 Day's discussion of char to that made of his account of 

 trout. 



In the account of the American char, Salmofontiiialis, 

 we have again a minute description, with no specific 

 diagnosis. In a footnote to this portion of the work, it is 

 pointed out that in the article " Salmonidne " of the 

 present edition of the "Encyclopaedia Britannica" the 

 erroneous statement of Dr. Giinther, that the Salmo 

 naniayciish of America is a true trout, is repeated, but no 

 reference is given to any work where the correct descrip- 

 tion of S. namaycush as a char can be found. 



We have up to this point been criticizing Mr. Day's 

 work chiefly from a speciegraphical point of view ; we 

 must now say a few words about the treatment of other 

 branches of the subject. At the beginning of the account 

 of the genus Salmo is a short description of the anatomy 

 of Salmonoid fishes, followed by a discussion of the eggs 



and iheir development, the latter especially in connection 

 with pisciculture at Sir J. Mailland's establishment at 

 Howietoun. The description in the text of the mode of 

 packing eggs which has been perfected at Howietoun 

 seems to be erroneous : it is stated that the main principle 

 is to employ thin layers of well-picked and pressed moss 

 in trays with perforated bottoms, the eggs being separated 

 from the moss by muslin mosquito netting, swan's down, 

 calico, or butter cloth ; while in a quotation in a footnote 

 the correct account is given — namely, that the ova rest 

 in direct contact with the damp moss, and are covered 

 by another layer of the same, the muslin being only used 

 in order that the layer of moss may be lifted and moved. 

 Reference is made in this part of the book to the subject 

 of hybridization between different species of Salmo, and 

 a review of the history of the subject is given, but the full 

 treatment of the subject occurs in a chapter specially 

 devoted to it. In this chapter details are recorded of 

 definite experiments in hybridization made at Howietoun, 

 This chapter on hybrids is one of the most interesting 

 in the book, and another on monstrosities is also well 

 worth study. 



Scattered throughout the pages are examples of that 

 originality in sentence-construction which is familiar to 

 all who know Mr. Day's writings. Thus in the account 

 of artificial fertilization we read : "This is gently stirred 

 with the hand until the eggs harden, or ' frees ' as it is 

 termed, being a period from one to three quarters of an 

 hour according to the temperature, taking longest in cold 

 weather.'' In another place we find : " One modifying 

 circumstance in the feeding of the salmon has been 

 observed to be connected with a muddy state of the river, 

 possibly interfering with respiration, consequent upon the 

 amount of mud which had been swallowed." Another 

 passage which is worth quoting is : — "As regards thirst it 

 would seem either to ba unknown to these creatures ; or, 

 living as they do in a watery medium, it may be quenched 

 by means of endosmosis through the skin. Were this 

 not the case, it would be difficult to conceive how such a 

 longing could be satisfied while residing in salt water." 



But in spite of its defects the book contains a mass of 

 new and accurate information concerning the forms of 

 Salmonidit of which it treats. In bibliography it is un- 

 usually rich, the results of previous writers being freely 

 quoted in footnotes, so that several of the pages contain 

 90 per cent, of notes and only 10 per cent, of text. 

 Besides the woodcuts in the course of the work, there are 

 twelve plates of illustrations at the end, ten of which 

 represent different forms of Salmonidte in beautifully 

 coloured lithographic impressions. The excellence of 

 these is very great, and testifies to great care and skill on 

 the part of the draughtsman {i.e. the author himself), the 

 colourist, and the lithographer. 



THE ECHINOIDEA. 

 Die Japmiischen Seeigel. Von Dr. L. Doderlein. Pp. 59, 

 PI. I.-XI., Th, I., Fam. Cidarida^ and Saleniidas. 

 (Stuttgart : E. Schweizerbart'sche Verlagshandlung, E. 

 Koch, 1887.) 



DR. DODERLEIN has produced the first part of a 

 very philosophical study of the beautiful Echinoidea, 

 which are in their paradise in the Japanese seas. Some 



