AND THE DEVELOPMENT OF THE MYRIAPODA. 127 



longer than the others. The single ocellus has disappeared, and in its stead three 

 distinct ocelli, arranged in a triangle, have been developed. The apex of the tri- 

 angle is directed upwards. The ocelli are of two sizes, the largest, a single one, being 

 at the posterior angle. The development of an increased number of ocelli in lulus 

 at successive periods was discovered by M. Gervais, but the precise time of their ap- 

 pearance has not before been indicated. The new segments of the body produced at 

 the former change of the animal, from the eighth to the twelfth inclusive, are now of 

 the same size as the original ones, and each has developed from it two additional pairs 

 of legs, so that the whole number of legs is now thirty-four. The thirteenth, or if 

 we may so term it, germinal segment of the last period, is less developed than the 

 preceding ones, and is distinguished from them by the circumstance that it is smaller, 

 possesses no legs, and has no lateral spot, which exists, as above stated, on each of the 

 preceding segments, to the seventh, marking the existence of the foramina repugna- 

 toria. The large patch on the seventh segment is now larger and darker than here- 

 tofore, and the spots on the succeeding segments have been increased in size. The 

 germinal space (13.^), which existed in the preceding period, and was then seen to be 

 forming segments, is now developed into six new apodal segments, from the fourteenth 

 to the nineteenth inclusive, very much smaller and shorter than the rest ; and a ger- 

 minal space {h) is again forming between the last of these and the penultimate seg- 

 ment of the body, which, as above stated, undergoes no marked change. The whole 

 body is thus composed of twenty-one segments, including the head. The first twelve 

 of these are now perfectly developed, as well as the last two, the intermediate ones 

 being only in their preparatory states. The antennae, parts of the mouth, legs, and 

 anal segments, are still covered with minute hairs. At this period I gave my speci- 

 mens for food some decayed leaves and rotten bark of the elm, as also some uncooked 

 potatoe, on which they seemed to feed voraciously. They seemed to thrive most 

 rapidly on the decaying bark, and grew daily, especially at the posterior extremity 

 of the body. 



On the sixty-second day (fig. 22.) all the specimens had been lying quietly coiled up 

 in a circle for nearly twenty- four hours, preparatory to again changing their skin. The 

 segments, from the thirteenth to the eighteenth inclusive, which had been partially 

 developed at the last change of skin, were now nearly completed, and exhibited the 

 transverse impression of the perfect animal ; and the future spots on the sides of 

 these segments were now shining faintly through the old skin, which had become 

 whitened and dried, exhibiting the peculiar appearance of the approaching change. 

 Besides this, instead of the three ocelli developed at the last change, there were now 

 five, which appeared through the tegument, still arranged in a triangle ; one of these 

 was larger than the last, and distinctly formed of two parts, so that six ocelli were now 

 about to appear. The number of legs still continued the same as at the last change. 

 The nineteenth segment, which, at the period of transformation, was but a very soft 

 fold of the tegument, with a slight division in the middle of it attached to the 



