22 



The Canadian Field-Naturalist 



[Vol. XXXIII. 



came on so unexpectedly that there can be little 

 doubt but what all the Blue Birds that ventured so 

 far north at that time must have perished. 



The consequence was that there was practically 

 an entire absence of these birds in this district the 

 following summer. 



F. L. Farley, 



Camrose, Alberta. 



On the early life-history of the American 

 LOBSTER (Homarus americanus). — Were this tiny 

 creature, just after it has emerged from the 

 egg, to be enlarged to say ten inches in length 

 and a regular ten-inch long lobster put along 

 side of it, two forms, quite unlike in general 

 appearance would be seen. The reason for this 

 difference in general form is because whilst 

 the mature lobster crawls about upon the bed of 

 the sea, the little juvenal does nothing of the kind, 

 but swims, or rather floats upon its back, through 

 the water or near the surface of the water. It 

 would be interesting to follow out in detail how this 

 most valuable of all crustaceans becomes more and 

 more modified as it passes from moult to moult, but 

 it must suffice for the present to point out that by 

 the time the lobster has acquired the crawling mode 

 of locomotion it has not then reached an inch in 

 length. Obviously the free swimming mode of 

 movement is primitive, and there are crustaceans, for 



instance the phyllopods, which swim upon their 

 backs throughout their life-histories, but in the case 

 of the decapods, which stand higher in the scale 

 of crustacean life, and to which shrimps, crabs, and 

 the lobster belong, this phenomenon is usually only 

 temporary, and in the case of the lobster is purely 

 so. Now when the mother lobster, guided by her 

 instincts, approaches the more shallow parts of the 

 sea in order that her eggs may hatch off her swam- 

 merets, and once the eggs are all hatched off, her 

 maternal duties are over, for that is all the maternity 

 she has. The young nauplii are now left to their 

 own resources. It was a wise provision of nature 

 that led the mother lobster to the shallows, for the 

 little helpless creatures are there defended against 

 many dangers which would have been encountered 

 further out at sea. Furthermore, they undoubtedly 

 meet there with a plenteous supply of surface food. 

 Nor is this all. In the sheltered harbors and bays 

 the little lobsters have an opportunity to undergo 

 their metamorphosis until as little crawling creatures 

 they seek refuge among the sea-weeds and under 

 the rocks ; from which time on they become better 

 and better equipped, through increase in size, a 

 shell hardened with carbonate of lime, and a pair 

 of powerful claws, to protect themselves at consider- 

 able depths in more exposed parts of the bed of 

 the sea. 



Andrew Halkett. 



BOOK NOTICES AND REVIEWS. 



Injurious Insects and Useful Birds. By 

 Prof. F. L. Washburn. J. B. Lippincott Company, 

 Philadelphia and London; 414 illustrations in text 

 and four coloured plates. Price $2.00. 



This volume prepared particularly for high 

 schools and agricultural colleges is largely the re- 

 sult of 21 years of work in economic entomology on 

 the part of the author. It will of course also be 

 a useful work of reference for gardeners and farm- 

 ers generally. Chapters one to six deal with the 

 losses to agriculture due to insects and rodents; farm 

 practices to lessen these; external structure of in- 

 sects; callecting and preserving insects; insecticides, 

 spraying and fumigation. Chapters seven to 

 eighteen discuss insect affecting various crops, such 

 a« apple, pear, small fruits, grain, roots, etc. 

 Chapter XIX on "Our Insect Friends"; XX, "The 

 Relation of Birds to Agriculture" and XXI, "Some 



Fcur-Footed Pests of the Farm," complete the 

 volume. — A. G. 



Outlines of Economic Zoology. By Albert M. 

 Reese, Ph.D., Professor of Zoology in West Vir- 

 f:inia University. Philadelphia, P. Blakeston's Son 

 & Co. 316 pages. 194 illustrations. 



This volume which has been based upon a brief 

 course in economic zoology given by the author 

 for several years in the above university, will be 

 found of special value to students, not only those 

 who are taking courses in general zoology, but also 

 those who are interested in agriculture. The book 

 is divided into fourteen chapters, as follows: I, 

 Protozoa; II, Porifera; III, Coelenterata; IV, 

 Echinodermata; V, Platyhelmenthes; VI, Nema- 

 thclmenthes; VII, Annulata; VIII, Mollusca ; IX, 

 Arthropoda; X to XIV, Chordata. The importance 

 of the study of economic zoology is becoming more 

 apparent every day. — A.G. 



