?74 



HAKDWICKE'S SCI EN CE-GO S S IP. 



head, and are more insect-like than in the rest of 

 the Thysanuradse. The females in both species are 

 furnished with ovipositors; that of the marine 

 species is of extreme lengtli, but the few specimens 

 I have seen of the inland one ^have had much 

 smaller developments of this, and indeed of all the 

 tllamentous limbs. 



Fig. 18/". Inland Petrobius, x 8, from North Wales 

 and Devonshire. 



Tlse marine species carries its antenna? out 

 straight before it, while the inland species doub'.es 

 them over its shoulders, so to speak. 



Fig. 188. Petrobius inanlimiis x 8. 



When turning over the stones at the foot of the 

 cliffs of the Dorset coast, one often comes across 

 the homes of P. maritimus. Under tliese circum- 



stances, they are found in dozens, to say the least 

 of it. Attached to the stones one turns up, too, are 

 found the exuvife in abundance, looking almost 

 lifelike ; and these, while the frightened creatures 

 are jumping frantically in various directions, mystify 

 the eye of the inexperienced, and make him faucy 

 the Petrobius is there iu hundreds. 



To catch the living insects, then, needs no little 

 dexterity, as they are wary and active to a sur- 

 prising degree. 



Petrobius is, however, fond of wandering over 

 the rocks iu the sunshine, and when thus met 

 singly, he may be coaxed iuto a test-tube by means 

 of a camel-hair brush, without much trouble. 

 You must be cautious in your approach, liowever, 

 for if alarmed, he will jump and run from rock to 

 rock so nimbly, that your shins and ankles will 

 probably suffer if you follow him up. 



1 suppose the Petrobius feeds chiefly at night 

 upon the decaying seaweeds, and other rejectamenta 

 of the deep, which are within easy walking distance 

 of his dwelling. I guess this because I have never 

 seen them feeding, and have been always unable to 

 keep them alive long in confinement— not more 

 than a day or two. A fine large specimen will die 

 in a few hours if shut up in a bottle or a large cell. 

 In colour, the P. maritimus is of a warm brown, 

 with dark patches and olive-green reflections. 



The scales are very various in their appearance, 

 and very beautiful. So also are those of the inland 

 Petrobius ; indeed I think they are the best, though 

 they are very sirailai- to those of P. maritimus. 

 The colour of the inland, species is vexy similar to 

 the marine one : my specimens, from North Wales 

 and Devonshire respectively, were, if anything, 

 rather the darkest. 



The specimens sent me from North Wales were 

 found under stones, and my Devonshire specimen 

 was caught after harvesting, at the bottom of a van 

 which had been emptied of its load of corn, amid 

 beetles and other creeping things galore. 



I hope shortly to renew the subject, and submit 

 some notes respecting the remainder of the Thy- 

 sanuradse. S. J. McIxtire. 



SNAKE-STONES. 



T) Y this term, gentle reader, we do not mean the 

 ■^-^ porous bodies, commonly so called, which Sir 

 Emerson Tennent and others have shown to be used 

 by the natives of Ceylon and elsewhere for the pur- 

 pose of absorbing the poison from snake-wounds. 

 In Scott's " Marmion " may be found a traditiuiuil 

 reference to quite another kind of " Snake-Stones ": 



" And how the nuns of Whitby told 

 How of the countless snakes, each oiie 

 Was turned iuto a coil of stone, 

 W^lien holy Hilda prayed. 

 Themselves, within their sacred bounds, 

 Their stonv coils had often found." 



