May 1, 1866.] 



SCIENCE-GOSSIP. 



101) 



Berkeleya has the valve in both side and front 

 view linear-lanceolate, obtuse at the tips. The 

 frustules are included in definite gelatinous filaments, 



Fig. 112. Berkeleya fragilis. a x 10. Ax 200. n x 400. 



which unite at the base in a tubercle. The only 

 British species is Berkeleya fragilis (fig. 112). 



Schizonema has the valves boat-shaped (navicu- 

 loid) . The frustules are in lines within a thread-like, 

 branched tube, of nearly equal diameter through- 



Fig. 113. Schizonema Grevillei. a x 5. b x 400. c x ioD. 



out. Schizonema Grevillei (fig. 113) is one of eleven 

 British species. 



Micromega has the'valves also boat-shaped, with 

 the valves arranged in the same manner as in 



Fig. 114. Micromega helminJAosum. 

 a Nat. size, b x loo. c x 4C0. 



Schizonema, but the thread-like tubes are united 

 into a flat, membranaceous, leaf-like frond. We 



have upwards of twenty British species, [of which 

 the one selected for illustration is Micromega helmin- 

 thosum (fig. 114). 



The genera which we have illustrated in the 

 present and two preceding numbers, constitute the 

 group of Navicular Diatoms in which the valves 

 have similar ends and a median longitudinal line, 

 and are either linear or quadrangular in the front 

 view. This group is called Naviculeje. The British 

 species are enumerated in Gray & Carruthers' 

 " Handbook of British Alga?," page 104 to page 116. 



CADDIS-WORMS. 



A BOUT this time last year I derived so much 

 -*-*- pleasure from a few caddis larva?, that I 

 should like to induce any who have never tried 

 such experiments to do so, promising them a last- 

 ing fund of enjoyment. In the " Scientific Sum- 

 mary " of Popular Science Review for January, 

 1864, was an account of experiments made by Miss 

 Smee in regard to the building capabilities of the 

 caddis-worm. Afterwards I read an article by the 

 same lady in the Intellectual Observer, in which she 

 gave a most interesting history of her experiments. 

 If Miss Smee could force these little creatures to 

 build of such a variety of things, why should not I ? 

 Already I had dozens of the larvae in my aquarium, 

 and, following Miss Smee's directions, I broke dif- 

 ferent coloured glasses into tiny bits, also pearl and 

 gold beads, fragments of coral and shell comb, 

 placing them in saucers of water ; then the larva 

 had to be turned off its case. This can only be done 

 by gently irritating the tail with a needle or pin, as 

 no force will induce it to leave its home with life, 

 the last segment being provided with two strong 

 hooks, with which they cling so tenaciously to the 

 case, that they will suffer themselves to be pulled in 

 two rather than release their hold. These hooks 

 can be easily seen with a pocket lens. Very soon 

 after the homeless larva has been placed among 

 the bits of glass, &c, it will commence to construct 

 a new case. I never remember experiencing 

 greater delight than I did in watching the " water- 

 maggots " adapting substances so novel to their 

 own requirements, cementing each fragment firmly 

 and no matter how diverse the size and shape of the 

 materials used, always keeping the inner surface 

 perfectly smooth and even. The caddises are not 

 long in building, and the addition of a few purple, 

 green, or bine glass cases, with here and there a 

 shining bit of gold or pearl bead, makes a pleasing 

 variety in the aquarium. I had one fine larva last 

 spring, which built entirely of thin white glass, 

 through which every movement of its body 

 could be plainly seen. The first day it was placed 

 in the aquarium it occasioned quite a com- 

 motion amongst the pugnacious sticklebacks, which, 



