244 



Zoology. 



Developement of the Eggs of Spiders. — In spiders* eggs, M. Harold has 

 observed a membrane corresponding to the shell of those of birds, also the 

 white or albumen and the yolk and scar. But the yolk has no proper 

 membrane, though it passes into the intestinal canal. The scar is also ob- 

 servable, and disperses itself in granules ; and the vv^hite, instead of being 

 absorbed by the young animal, as in birds, is the matter out of which is 

 formed all its members, a circumstance that constitutes the principal dif- 

 ference between the eggs of birds and spiders. 



The eggs of spiders, which are laid in the autumn, remain throughout the 

 winter enclosed in a silken web ; on the approach of summer they gradually 

 change into their active perfect form. The progress of this transformation 

 has been M, Harold's study, and his observations are detailed with great 

 perspicuity in his Unters, uber die Bildungsg. der Wiebellosen Thiere im Eie. 

 The eggs, in their dormant state, every body knows, are very small 

 iftg.lO. a) ; magnified (6), the scar or germ is discern- 

 ible (c"). The first change is this germ dispersing its €>** 

 granules into the albumen, which attach themselves 

 to the vitellus, or yolk ; and, after being expanded in 

 this manner, it assumes the figure of a comet in the 

 interior of the mass. When the albumen becomes as 

 it were saturated with these grains from the germ, or 

 vital principle, it is then called colliquamentum ; and, 

 when sufficiently coagulated, is for the present called ^^ 

 cambium. This cambium becomes divided into two 

 Dnequal parts : the smaller portion {fig. 71. a) being uppermost, is called 

 the cephalic cambium,\t being that from which the head 

 of the animal is afterwards formed ; and the greater 

 portion (6), situated below, is called the thoracic cam- 

 bimn, from which the body is composed. Soon after 

 this division of the cambium, it is seen marked with 

 the rudiments of the limbs and other parts, eyes, 

 breast, &c. ; next, the lower extremities become 

 moulded from that portion of the cambium called the 

 abdominal. In process of time all the parts of the frame 

 have gained form and consistence, the animal secre- 

 tions commence, and the actions of the legs 72 

 and palpi begin by throwing off the thin skin 

 which enveloped the whole mass. {^g. 72.) 

 Some time passes before the young spider is 

 very active ; he feels a kind of torpor until 

 his frame is sufficiently fitted for his wander- 

 ing predatory life. It was on the eggs of the 

 ArknesL diadema that M. Harold made the 

 observations, from which the foregoing is a 

 brief extract. — J .M. 



Musical Snails. — As I was sitting in my room, on the first floor, about 

 nine P.M. (4th of October last), I was surprised with what I supposed to be 

 the notes of a bird, under or upon the sill of the window. My impression 

 was, that they somewhat resembled the notes of the wild duck in its noc- 

 turnal flight, and, at times, the twitter of a red-breast, in quick succession. 

 To be satisfied on the subject, I carefully removed the shutter, and, to my 

 surprise, found it was a garden snail, which, in drawing itself along the glass, 

 had produced sounds similar to those elicited from the musical glasses. — 

 Sam. Woodward. Diana Square, Norwich, Aprils. 1829. 



Developement of the Eggs of the Common Crab {Cancer Pagurus, L.) — 

 In a late number of his Zoological Researches, Mr. J. V. Thompson of 

 Cork has given some additional particulars relative to the animal of the 

 supposed genus Zoea, which he considers as the larva of the common crab. 



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