Feb. 1, 1S66.] 



SCIENCE-GOSSIP. 



29 



of July evenings*. The caterpillar, 1 believe, feeds 

 on the wild convolvulus ; many specimens were 

 obtained by the writer at Battersea. 



The minute moths which affect our hawthorn 

 hedges, rose-bushes, &c, are too numerous to 

 specify. They are, besides, when procured, so diffi- 

 cult to mount without injury, that the task is almost 

 impossible. These tiny Lepidoptera may be com- 

 pared to the humming birds, and the prismatic lines 

 in both seem to be analogous. 



It is very odd, but no less true, that the precise 

 nature of the iridescence, both in the feathers of 

 moths and the scales of insects, is scarcely under- 

 stood. In some scales there are doubtless real 

 colours present, but in others the effect seems to be 

 brought about by the decomposition of light. 



x\n opinion which obtains greatly is that each 

 scale is a laminated structure, and that in many 

 cases the inner laminae contain the colouring matter 

 (if colouring matter it be), while the outer ones are 

 corrugated and quite transparent, and this is the 

 cause of the brilliant reflections. Mr. Gosse says, 

 " It is by the separation and reflection of prismatic 

 hues that they appear beautiful, but by what law 

 some reflect none but red, some none but yellow, 

 some none but blue rays, we know not."f 



S. J. MTntire. 



GILL-EANS OE SABELLA. 



JL. D., writing at p. 262, vol. i., asks if it is a com- 

 • mon occurrence for Sabella) to cast their gill- 

 fans? Yes, very common; so much so that when Ihave 

 some specimens of S. voluticornis (a very line species) 

 sent me from England to Hamburg, I never expect 

 to find them arrive with their gill-fans attached, but 

 I always get them separated in transport, and lying in 

 the vessel they came in. But I place the animals in 

 a good stream of shallow sea-water, in one of the 

 hospital tanks of this establishment, where they are 

 unmolested by other creatures, and where they get 

 more air in the water than in the show-tanks. In the 

 course of two or three weeks, or a month, according 

 to the season, very small and tender gill-plumes have 

 grown (to replace the old ones), and these just peep 

 out from the ends of the tubes. They then grow 

 quickly, and in the course of a month longer are 

 transferred to the tanks, where the public can see 

 them. But the new fans thus grown, though in time 

 they get to be as large as the original ones, are 

 always whiter and more delicate-looking than those 

 they had when in the sea. 



I have verified, with Sabella penicillus, S. casta, 

 S. bombyx, and others, all that Sir John Graham 

 Dalyell observed with respect to the manner in 



* I saw one this evening in London, Nov. 2. I860, 

 t F. H. Gosse's " Life, its lower and intermediate Forms," 

 page 163. 



which the tubes of these animals are added to at 

 both ends. With me, as with him, Sabella; when 

 they arrive here in separate tubes, like so many 

 sticks, instead of being fastened to some firm sub- 

 stance, give no signs of life, until they have bur- 

 rowed their posterior extremities in the sand of the 

 aquarium, and this they do very quickly, not caring 

 if they cannot make a new portion of their tubes of 

 mud (of which the tubes consist when in the sea), 

 but continuing it in fine sand. When thus fixed, 

 they raise themselves up from the horizontal position 

 as when first placed in the aquarium, and expand 

 their gill-fans, and live well for long periods. 

 Serpula contortiiplicata too, with me, does not display 

 itself at first, nor till I have kept it a week or two. 

 Sabella tubularia (now Protida protensa) I find very 

 handy. Some time ago, I, by accident, laid one down 

 in a tank, with the mouth of its tube close against 

 an upright piece of slate, so that the animal could 

 not emerge, but it soon got over this difficulty by 

 adding to its tube a new piece of about an inch 

 long, turned abruptly at right angles to the original 

 tube, and then, of course, the gill-fans expanded as 

 usual. 



Much information may be got about annelids from 

 an octavo book published this year, at seven 

 shillings (pp. 365, with twenty plates), entitled, 

 '" A Catalogue of the British Non-Parasitical Worms 

 in the Collection of the British Museum. By George 

 Johnston, M.D." This, though called "a catalogue," 

 is not a dry list, but is a very readable book. The 

 late Dr. Johnston, of Berwick-on-Tweed (1793 — 

 1855), was indeed such a genial man that he could 

 never be dull. The volume is enriched with copious 

 extracts from the writings of two other naturalists 

 of the same class — those who observed the lower 

 aquatic marine animals in a living state : Colonel 

 George Montague (he died in 1S15) and Sir J. G. 

 Dalyell (he died about 1852)— which is a valuable 

 feature of the work, the books of these two natural- 

 ists being expensive. I greatly admire their style 

 of treating their subjects, their descriptions being 

 both exact and vivid, and given in a manner which 

 makes one feel intuitively that they had the living 

 animals before them, and that they really loved 

 them. Dalyell is especially felicitous in his language ; 

 for example, in describing the suddenness with which 

 the gill-fans of Sabella peniciltus collapse, he says, 

 "Let the slightest shock be communicated, and the 

 whole instantaneously collapses and disappears 

 within the tube, almost before its image lias faded 

 from the eye." 



Every one who has seen a tuberculous annelid flash 

 out of sight, must feel how strikingly truthful are 

 those words which I have marked in italics. 



Some years ago, when collecting materials for the 

 history of the aquarium, I applied to the late Miss 

 E. Dalyell, the venerable sister of Sir John, for any 

 information she could give me respecting the system 



