356 Analysis of Scientific Books and Memoirs. 



swimmers on each side is seven ; they are covered with hairs, and in the 

 specimens exiimined a vast number of voriicel/a or bell polypi were at- 

 tached. They sometimes infest this species of larva to such a degree, as 

 considerably to impede its motions in swimming. On each side of the ab- 

 domen, which commences near the origin of the first pair of tracheae, or 

 swimmers, arise the great vessels, of a light blue colour ; the rest are pro- 

 bably united near the tail, where an exceedingly curious process is also 

 distinctly exhibited. The whole surface of the body is thickly covered 

 with hairs, and several tufts are disposed in clusters, with some regulari- 

 ty, down the back and sides, are so much more distinct. 



The flexible pulsatory organ before alluded to, is in perpetual motion. 

 It resembles the letter S inverted : it, however, varies a little during its vi- 

 brating motions in the intestinal canal. The use of the curious appenda- 

 ges at the lower extremity of the body is unknown- Its tail is biforked 

 and crustaceous. As it approaches maturity it casts its skin several times, 

 from each of which it escapes by a rent formed down the back. 



After this creature has remained for a considerable time in the larva 

 state, it buries itself in a hole, which it forms for that purpose near the 

 edge of the water, and after passing through the chrysalis state, it emer- 

 ges in the form of a perfect beetle." 



III. — A Flora of Berwick upon Tweed. By George Johnston, M. D. 

 \ Fellow of the College of Surgeons, &c. Vol. I. PHiENOGAMOus 

 'Plants. Edin. 1829. 12mo. Pp.250. 



A few years ago the Society of Arts for Scotland recommended a minute 

 examination of the natural history of this country, and offered prizes for 

 the best papers on the mineralogy, geology, or botany of counties or parti- 

 cular districts. One or two good memoirs, we believe, were transmitted to 

 the society, but no zeal has been shown by the few who are qualified for 

 the task to carry the Society's views into effect. 



The present work of Mr Johnston on the Flora of Berwickshire is a 

 model for memoirs of this description, and we anxiously hope that our 

 clergymen and medical practitioners, who are peculiarly fitted for such in- 

 quiries, will follow the excellent example which has been set to them. 



The unoccupied time, which, on his entrance into business, falls to the 

 lot of almost every physician, was devoted by our author to the examina- 

 tion of the indigenous plants of his neighbourhood, and the catalogue of 

 his discoveries gradually increased till it assumed the form which it now 

 bears. 



*' The chief object of the book," says Mr Johnston, " is to give such a 

 description of the plants growing wild in the vicinity of Berwick, as may 

 enable any one acquainted with the elements of the science, to ascertain 

 the names by which they are known ; and it will likewise serve as a guide 

 to conduct the inquirer to the places where the rarer species are to be 

 found. The utility of a work of this kind, consists in its facilitating the 

 investigation of species to those resident within the limits of which it 

 treats, by lessening the objects of comparison ; while others may find in 



