213 Bihliographical Notice, 



is illusory. In numerous trials, particularly on fine English 

 specimens from Hull, sent us by Mr. G. Norman, we have en- 

 tirely failed (with glasses, too, of unsurpassed excellence) to bring 

 out regular, distinct, and unmistakeahle striae — such as would be, 

 at once, so recognized by an eye practised on the strise of other 

 Diatoms. 



After all, it is not improbable that true striae, yet unresolved, 

 may exist on the valves of this species, and furthermore, that the 

 apparent striae of different observers may be similar to the spec- 

 tral or spurious lines before noted as occurring on the bands of 

 Nobert\s test plate when examined by an objective incapable of 

 resolving them. 



A summary of the foregoing may be briefly stated thus : — 

 Our experiments lead us to believe, 



1st, that lines on Nobert^s test plate closer together than 

 about the g=^th of an inch cannot be separated by the modern 

 objective. 



2nd, that no ti-ue striae have yet been seen on the valves of 

 Amphipleura pellucida. 



3rd, that the alleged variableness in the striation of Diatoms 

 among individuals of the same species has been greatly exagge- 

 rated ; on the contrary, we find a remarkable uniformity, thus 

 sustaining the opinion of Prof. Smith*, that, for characterizing 

 species, " striation is the best guide.^' 



Columbus, Ohio, Nov. 1860. 



BIBLIOGRAPHICAL NOTICE. 



Suggestions for forming Collections of Birds' Eggs. By Alfred 



Newton, M.A., F.L.S., F.Z.S. London : E. Newman, 18G0. 



(Reprinted from the ' Circular ' of the Smithsonian Institution of 



Washington.) 

 The proper object of collecting birds' eggs is well expressed in the 

 introductory remarks of the ' Smithsonian Circular.' It is some- 

 thing more than the completing of a series of specimens. It is a 

 valuable means of obtaining a clue to the limits within which each 

 species rears its young, as well as a knowledge of its habits and pe- 

 culiarities during the breeding-season. Its nidification is an import- 

 ant chapter in the history of each bird ; and too little is known of 

 the nuptial garb of many species, and of the plumage of their nest- 

 lings, as well as of the form and markings of their eggs : yet all these 

 are points which cannot be neglected by the scientific ornithologist. 



Mr. A. Newton is well known as a writer on ornithology ; his 



name is also associated with perhaps the most complete collection of 



the eggs of European birds. The present pamphlet therefore 



carries with it the authority of long practice, and contains the sug- 



* Syn. Brit. Diat. vol. ii. Introd. p. xxvi. 



