430 Revieics — Br. Davidson^ BracMopoda. 



Thirty years have passed since the publication of the general 

 introduction to the first volume of this Monograph. Coincidently 

 ■with, and largely induced by, its progress, a vast amount of precise 

 knowledge has been acquired and made public, in regard to all that 

 relates to the history and distribution of the Brachiopoda. Indeed, 

 our knowledge of them, in any sufficient sense, may be almost said 

 to date from about the time when the learned author began his 

 labours ; and the earliest known reference to them in any printed 

 work dates only from 1606. The present appendix closes a series of 

 researches, begun just half a century ago, on the Brachiopoda of the 

 British islands. During that period, Dr. Davidson has not only pre- 

 pared the text of his monograph, and numerous collateral and 

 frequently very important papers on the general subject, but has 

 drawn with his own hand more than two hundred admirable and 

 artistic plates by which that text has been illustrated and adoi'ned. 

 Seldom has fortune equipped more completely a student for his life- 

 work than in the present case, when more than ordinary artistic 

 talent, a liberal education, independent means, were joined to unsur- 

 passed devotion in the pursuit of knowledge, and impartiality in the 

 recognition of the labours of others in the same field. 



The steady stream of information induced by the publication of 

 successive parts of the monograph has necessitated supplement after 

 supplement. The present and concluding part not only contains 

 such material, but a catalogue of, and index to, the British genera 

 and species, bibliographical and stratigraphical, and, more important 

 than either for the general biologist, a summary of progress in our 

 knowledge of the class up to the present time. This includes 

 notices, under separate heads, of the test, the embryology, the 

 affinities, the adult anatomy, habitat, and ranges in depth, of recent 

 species, characters of the fossil genera, and classification discussed 

 by families. Full space is allotted to the advocates of contending 

 theories : Kowalevski's valuable paper on the embryology is given in 

 full abstract, with excellent figures ; various suggested pedigrees are 

 quoted ; the brilliant rise, and slow but continuous decadence, of the 

 " worm theory " is related, with generous recognition of the sagacity 

 of Morse in the detection of affinities to which the then imperfect 

 knowledge of the molluscan pedigree, and his remarkable researches 

 into the early stages of Terebi'atulina and Lingula, lent a plausible, 

 but, as it has since proved, a one-sided interpretation. The general 

 conclusion is reached, that, however great the probability of 

 continuous descent, with modification, as an explanation of the 

 various forms of Brachiopods now or previously existing, the 

 palseontological record presents many facts inexplicable by, or even 

 opposed to, this theory ; while of natural selection there seems to be 

 absolutely no visible trace. The number of British forms which, at 

 the commencement of the work, comprised 13 genera, and 454 partly 

 invalid species, has now expanded to 74 genera, and 976 species, and 

 varieties, to which even now accessions continue to be made. 



In taking leave of his task, so worthily performed and to be con- 

 tinued by younger hands, the author, in spite of certain infirmities, 



