176 Zoological Collections. Invei-tebratn. 



it was found that, also during life, fluids are contained in their parietes. 

 Being kept in different gases, viz. nitrogen, oxygen, and carbonic acid, the 

 larva lived equally long in all, viz. about four days, and exhaled always the 

 same quantity of carbonic acid. 



The organs of generation are small vesicles, in which tracheae terminate. 

 No difference could be perceived between male and female. — Ihid. p. 555. 



Gland in the Gasteropodous MoUusca. — Dr Kleeberg, of Kbnigsberg, has 

 discovered a gland in Bulimus ovatus, Brug. which is not noticed in the 

 anatomical descriptions hitherto given of the Gasteropodous mollusca. 

 The gland is situate below the cesophagus, and the inferior ganglion of the 

 nervous ring. From the lower surface of the gland, between its principal 

 part or body and an anterior lobe with which it is furnished, an excretory 

 duct arises, which opens into a wide canal running within the substance of 

 the foot, and opening externally between the prominent anterior border of 

 the foot and the lower lip, Dr K. has found the canal in the Gasteropoda 

 pulmonata, indigenous to his own country, excepting the aquatic species and 

 the genus Succinea. In Limax and Arion injections would seem to prbve 

 that it communicates with the venous system. — Ibid. p. 574.r .^ 



The Brisdes of the Annelides considered as Organs of Defence. — MM. 

 Audouin and Milne Edwards, having studied with much care the structure 

 of the different external organs of the Annelides, and having directed their 

 attention to the bristles with which the feet are provided, are of opinion, 

 that these organs, which used to be regarded as mere ornaments, or, with 

 more reason, as locomotive organs, also serve for defensive weapons of a 

 peculiar nature. 



In the Tubicolce, as M. Savigny had previously remarked, they are modi- 

 fied in a particular way, so as to assist the motions of the animal in the 

 tube which it inhabits : but it is not less worthy of remark, that in the 

 Doi'sihranchicB, which generally lead an erratic life, the bristles have different 

 and no less important functions. MM. Audouin and Milne Edwards have 

 observed, that they in general take on the form of spines or stings, the 

 more formidable that they are retractile, and that the animal can direct 

 them at will against any object whose attack it fears. Their form is always 

 in accordance with this use, and their structure is varied. 



The term hairs sometimes expresses their appearance appropriately, as 

 well on account of their extreme fineness, as of their brilliant yellow colour. 

 Such are the flexible bristles of certain Aphroditce. These bristles, which 

 sometimes, as in the Aphrodita acideata, intertwine, so as to forin a sort of 

 felt, have no other use than to protect the body, in the same way as the 

 coat or fleece of a quadruped. In this case, their function is entirely passive, 

 and the animal cannot retract them, or direct them against any dangerous 

 object. When examined under the microscope, they appear simple, and 

 without any of the denticules which are found in others. Another kind are 

 also simple, but stiff, stout, retractile, and sharp-edged. These the animal 

 can make use of as so many pins for its defence. Often, again, the 

 hairs, though simple, have a somewhat wove, complicated organization : 

 they may terminate in a sort of fork, with two unequal branches, or present 

 a groove, with toothed margins. Finally, they sometimes represent, in the 

 disposition of their point, a lancet or spear, whose raised edges are serrated. 



Here, then, we have certain annelides provided with stilettoes, prickles, 

 and divers other formidable weapons fit for defence j and they have them 

 in great abundance grouped in fasciculi on each of the feet, which in some 

 species amount to upwards of six hundred. 



However, these microscopic weapons are much less curious than those 

 whose structure MM. Audouin and Milne Edwards have made known, 



