242 Zoological Collections, Inveitebrata. 



From his observations, it appears, that the genera Dipsasy Homalopsis, 

 or Cerberus, ought to be classed among the venomous serpents, as w^ell as 

 several species of Colubri hitherto confounded with the harmless Colubri, 

 and of which it is necessary to form a new genus. M. Duvernoy has 

 discovered in these serpents, behind the series of maxillary teeth, another 

 lai'ger tooth, separated from the first by a vacant interval, and hollowed by 

 a more or less marked groove along its convexity. But besides this grooved 

 fang, which is always found behind the series of maxillary teeth, the serpents 

 in question have also a venomous gland, occupying the place of the supra-^ 

 maxillary salivary gland of harmless serpents, or the venomous gland of 

 common venomous serpents. 



In these latter, ( Crotali, Viperce, Sfc.) the venomous gland consists, accord- 

 ing to the researches of M. Duvernoy, of a soft and spongy substance, 

 protected by a more or less thick fibrous envelope, and having a single excre- 

 tory duct, which opens at the base of the fang. This gland is always 

 connected with the anterior temporal muscle, which is detached in great part 

 from the temples to be fixed to its capsule ; it has, therefore, the remarkable 

 character of possessing a voluntary muscle for compression. In serpents with 

 posterior fangs, the venomous gland is equally soft, spongy, and not granu- 

 lated : circumstances which distinguish it from salivary glands, as has been 

 already observed by Schlegel ; but it never has that thick and fibrous enve- 

 lope which every where covers the venomous gland of Viperce, Crotali, and 

 other venomous serpents, properly so called. In serpents with posterior fangs, 

 the anterior temporal muscle is scarcely connected with the gland, which it 

 covers a little in some cases, undoubtedly to compress it also, but under 

 which it descends in other cases, as under the supra-maxillary gland in the 

 harmless Colubri. 



In serpents with posterior fangs, as in those with anterior ones, the 

 supra-maxillary gland has been interrupted in its development, and is some- 

 times found reduced to the most rudimentary state. The lachrymal gland 

 is always, in the harmless Colubri, of a size equalling at least the ball of the 

 eye ; placed chiefly behind the orbit, it appears to have as important a 

 function in the venomous serpents with posterior fangs, as in harmless 

 serpents ; whilst, in the common venomous serpents, it is frequently reduced 

 to its small intra-orbitar portion. In this case, the anterior temporal muscle, 

 which no longer compresses it, belongs more exclusively to the venomous 

 gland. 



The venomous apparatus of serpents, with posterior fangs, is, therefore, 

 much less perfect, much less fit for attack, for piercing a wound, and distil- 

 ling venom into it, than that of serpents with anterior fangs. The veno- 

 mous gland can scarcely be compressed in some species by the anterior 

 temporal muscle ; in other species, it is entirely incapable of this action. 

 Besides these imperfections, the generally smaller size of the posterior 

 fangs will easily shew how the latter serpents are much less celebrated than 

 the venomous serpents, properly so called, the more active nature of their 

 venom not compensating for the imperfections of their dental apparatus. — 

 BuU. des Sci. Nat, Oct 1830. 



Eggs of the Planaria laciea M. Ch. Desmoulins has found, that in the 



space of twenty-four hours, the egg of the Planaria lactea, (which first 

 appears under the form of a milky white mass,) becomes perceptible in the 

 body of the mother, acquires its form and dimensions, becomes yellow, 

 reddens, is laid, and becomes completely black. When, however, the delivery 

 is a little premature and artificial, the egg does not become quite black for 

 several days. 



