June 1, 1865.] 



SCIENCE-GOSSIP. 



123 



I had found liim at last, and at Lome, so pounced 

 upon him as a lawful and legitimate prize. Knife 

 and hammer soon severed his close attachment to 

 the rocks ; and turning him up to take a peep at 

 his powerful ring of muscle and strangely-formed 

 breathing apparatus, I spied a worm evidently very 

 uneasy, about three inches long, brown, and in shape 

 like an ancient dagger-blade. He appeared to me 

 to be wriggling out from betwixt the folds of the 

 foot or the mantle, and apparently most anxious to 

 escape. 



My first impression was, that he was a captive 

 that by some mischance had got imprisoned under 

 the shell of the fissurella ; and thanking his lucky 

 stars for such a fortunate deliverance, wished to 

 make the best of his liberty, and rejoin his friends. 

 But in displacing other shells, I found in nearly 

 every one a similar tenant : the secret was discovered 

 — the worm was a parasite, that lived in peace and 

 good fellowship with Sir Keyhole, — recalling to my 

 remembrance Ossian's lines on the Pinna and the 

 parasitic crab — 



* One room contained them, and the partners dwell 

 Beneath the convex of one sloping shell, 

 Deep in the watery wastes the comrades rove, 

 And mutual interests bind their mutual love. 



That the parasite does no harm is clearly proved 

 by the healthy state of the mollusc in whose shell 

 it takes up its abode. How far mutual interest may 

 conduce to mutual friendship, I am unable to say. 



The illustration heading this article will give the 

 reader a good idea of the Eissurella and its para- 

 site. 



On more carefully examining the position of the 

 worm, I found it was invariably coiled away in a 

 semicircle under the foot, like a ribbon on its edge ; 

 never flat. This seems to me a wise provision ; for 

 the pressure of the muscles when the limpet grips 

 the rock would crush a soft-bodied worm to death 

 if flat ; but edge on, the position chosen, all risk of 

 liarm is avoided, as it fits in a cleft between two 

 layers of soft material. 



Tying several of them tightly round to prevent 

 the worm escaping, I brought them home in situ. 

 At least four out of every six contained a parasite, 

 and what is rather strange, the worms were nearly 

 all of one size. A query or two naturally suggest 

 themselves. How did this friend or intruder, which- 

 ever it may be, first get installed as a lodger ? Did 

 he get in as a baby, and thus become an adopted 

 child; or did he slip in as a full-grown annelide, 

 defying Sir Keyhole to turn him out ? How does 

 he procure food ; and on what does he subsist ? I 

 confess utter inability to give a satisfactory reply : 

 my impression, however, is, the parasite grows from 

 a minute germ (if that is a riglit term) iu the place 

 and position ia which I found it. 



I put them in sea-water, after taking them out of 

 their sanctuary ; but in no single instance did one 

 ever go back again. I tried to replace them, but 

 could never accomplish it, or induce the worm to 

 remain. Not that this proves anything, inasmuch as 

 experience teaches me any interference with the 

 regular habits of any of the lower forms of life is at 

 once resented ; and the power, or will it may be, to 

 adapt itself to altered circumstances is but slowly ac- 

 quired. I cannot conceive the possibility of a large 

 worm, the feet armed with curved bristles, like 

 bundles of minute fishhooks, being quietly permitted 

 to creep under tlie shell, force its way by crawling 

 round and round the foot, by a system of hook and 

 drag; for iu no other way could it edge in, without 

 worrying and enraging the fisstu'ella beyond all 

 power of endurance, ordinary pressure being only 

 needed to squeeze the intruder fiat as a pancake. 

 By gently tickling it with a bit of sea-weed under 

 the shell, one would say that patience was a virtue 

 but little cultivated by the fissurella ; the slightest 

 touch, and down goes the shell with a force that 

 cuts the weed in two like scissors. What chance 

 would a soft-bodied worm stand ? Not the slightest. 

 The parasite, like Topsy, was " raised " where it 

 lives. 



What part a worm, doomed, as far as we know, to 

 pass its whole life captive in the shell of a mollusc, 

 plays on nature's wide stage, is a problem beyond 

 human ken. We know nothing was created in vain 

 —that the tray diatom has its use ; and this insigni- 

 ficant annelide serves a purpose aud fulfils a destiny 

 in the endless maze of life, as important as the 

 lordly lion, or even man himself. 



Por the benefit of our scientific readers, we annex 

 the specific description of this new parasitic worm. 



Lepidonotus Loedi {Baird). — This species is 

 about 3 inches long, and rather more than one-third 

 of an inch in diameter at the broadest part of the 

 body. It tapers gradually from the head to the tail, 

 which is only about i of an inch broad. The colour 

 is of a light brown, a broad line of a much darker 

 brown running along the whole length of the centre 

 of the back. On the surface, a groove runs down 

 the centre of the body throughout its entire length. 

 The elytra are 35 pairs in number, thin, membranous, 

 and of a light-brown colour. The two first overlap 

 each other slightly in the middle ; but for the rest 

 of its length the centre of the back is uncovered. 

 The anteunse are five in number ; the central one 

 short, of much the same length as the internal ones ; 

 the two external ones the longest, white, with a 

 bright black ring round the upper part, but leaving 

 the point white, which is acute at the apex. The 

 feet are tolerably stout, and the two divisions are 

 both furnished with sharp but curved pointed 

 bristles. The superior cnrhi are white, and of a 

 moderate length ; the inferior ones being short. 



