M. Fabre on the Development of the Myriapoda. 165 



work. But what becomes of them ? and how do the}^ arrive at 

 the seminal receptacles of the females ? Of this we still know 

 nothing, and it is difficult to form any probable supposition ; 

 observation alone can settle the question. 



M. Fabre has observed the phases of development in several 

 genera of Chilopoda. Lithobius forcijjatus is born with ten 

 segments, seven pairs of feet, seven joints in the antennae, and 

 two ocelli. Two months afterwards, it has acquired its seven- 

 teen segments, its fifteen pairs of feet, twenty-six joints in its 

 antennae, and six ocelli on each side. 



He has found the young of Scutigera araneo'ides furnished 

 with only seven pairs of feet, and in all probability in tiie first 

 stage of their development. This species not only presents an 

 increase in the number of segments, legs, ocelli, and joints of 

 the antennae, but also in that of the joints of the tarsi. What 

 is most singular in this development is, that the segments which 

 bear the first seven pairs of feet, and which exist at the moment 

 of birth, form the half of the body which contains the organs of 

 the senses and the essential parts of the digestive apparatus ; 

 whilst the other half, which lodges the reproductive apparatus, 

 is developed subsequently. It appears therefore that this ante- 

 rior part represents the larva, which only manifests the life of 

 the individual, and the posterior part the perfect insect, in 

 which resides the life of the species. This distinction appears 

 the more evident, as the dorsal shield of the median region is 

 the largest of all, and differs so much from the others, that 

 Linnaeus called it the elytroni it covers three pairs of feet, of 

 which the first two belong to the young animal at the time of 

 its exclusion, and the third to the part of the body produced by 

 gemmation. It thus, as M. Fabre says, marks the separation of 

 the anterior portion of ovular origin, from the posterior portion 

 of gemmary origin. M. Fabre from this compares the develop- 

 ment of the Scutigera with the facts observed by Milne-Edwards 

 and Quatrefages in Syllis and the Myrianides. 



The development of Cryptops is especially interesting, because 

 the parts of the mouth are deficient in the young. With the 

 microscope nothing is seen but a rounded aperture, situated at 

 the extremity of the head, and fringed at the margins. It is 

 also to be observed, that as many as twenty-eight and twenty- 

 nine joints are found in the antennae of Cryptops Savignyi, 

 which afterwards have only seventeen : the original number must 

 diminish with age, either by amalgamation or by the casting of 

 some of the joints. 



