SCIENCE. 37 



objects selected for such elementary study, and to furnish suggestions 

 as to the way they can most readily be turned to good account. The 

 appliances recommended are of the most trifling cost. Even simple 

 lenses are not absolutely required for any of the studies suggested. 



Commercial and Other Sponges. {No. III.) 



By Professor Alpheus Hyatt. Illustrated by 7 plates. 4% by 6 inches. 

 Paper. 43 pages. Introduction price, 20 cents. 



This little manual gives an account of the sponges in common use, 

 and amply illustrates their processes of growth, and the methods of 

 obtaining them and preparing them for the trade. The skeletons are 

 present to the eye every day, and even the dullest scholar will under- 

 take with interest to find out their different qualities, their common 

 names, where they come from, and how they are formed. 



A Set of Eight Specimens has been prepared for the use of 

 classes taking these lessons, and will be furnished for $1.00. 



A First Lesson in Natural History. {No. IV.) 



By Mrs. Elizabeth Agassiz. Illustrated by woodcuts and 4 plates. 4^ 

 by 6 inches. Paper. 64 pages. Introduction price, 25 cents. 



A general history of hydroids, corals, and echinoderms, written in 

 narrative form, for very young children, under the direction of Prof. 

 Louis Agassiz. Amply illustrated. 



While scientifically accurate and clear, it is as simple and fascinat- 

 ing as a wonder story. No fairies could more completely win the 

 interest of children than do sea-anemones, corals, jelly-fishes, star- 

 fishes, and sea-urchins, as described and represented in this little 

 book. 



A Set of Twenty-four Specimens, to accompany Guides IV. and 

 V., will be furnished for $2.00. 



Common Hydroids, Corals, and Echinoderms. {No. r.) 



By ALPHEUS HYATT. Amply illustrated. 4%hf 6 inches. Paper. 32 

 pages. Introduction price, 20 cents. 



This pamphlet shows how the studies, or observations, arc to be 

 most satisfactorily made, and supplies such information as one ne</ S 



