254 Variatio7i in the Mealioo7^m, Tenebrio molitor 



h. The Antennae. 



The variations in these organs appear as a reduction, an increase, or 

 a deformity of the segments. A decrease of the number of segments is 

 not quite so rare as an increase, which was met with only twice. The 

 normal number of segments is eleven. 



No. 4. Cases were noted in which this number was reduced to 10, 9, 

 8, 7, 6, 5, 4 and 8 segments, or 



No. 5. The whole antenna was wanting, and for that matter, the 

 clypeus was imperfectly developed, though both eyes were present. 



Most of these reductions are only unilateral ; the other antenna is 

 often normal. The reduced antenna not infrequently bears indications of 

 the process by which that reduction was brought about, viz. by fusion 

 of two or more segments. 



Such a fusion may affect various segments, excepting the scapus and 

 the pedicellus in which no fusion was ever observed. 



No. 6. In those cases where the antennae consisted of nine or ten 

 segments it was often noticed that all nine or ten segments, of one or 

 both antennae, had a normal length and shape without any indications of 

 the reduction having been caused by a fusion of segments. 



No. 7. In some of these cases it was accompanied by a reduction of 

 the tarsal segments on all six legs. In one culture of about 100 beetles 

 this anomaly was observed nine times, which seems to be based on a 

 hereditary factor, but about which no particulars can be given yet. 



No. 8. An increase of the number of the segments is very rare. It 

 was found only twice, and not in a complete form. The case consisted 

 in the 9th segments in both antennae being abnormally enlarged, and 

 showing an obvious constriction, indicating that this segment is built up 

 of two joints. 



No. 9. Deformities, when the number of segments is normal, mani- 

 fest themselves in an enlargement or diminution of one of the segments, 

 in excrescences or spine-like processes, or in a fan-like arrangement of 

 the segments which are constricted then on one side only, 



c. The Prothorax. 



Many of the variations in the prothorax were of a quantitative 

 nature. They concerned the degree of development of some one or 

 other morphological character, slight differences, which, on account of the 

 smallness of the objects, were difficult, if not impossible, to express 

 quantitatively. The personal experience of the observer and his intimacy 

 with the material must decide his judgment of what is called weak or 

 strong. 



