An Instance of Mutation, 135 



to be classed separately, not only because the reduction 

 is by as many as four segments, but also because it is 

 inherited. There are only two cases on record which may 

 be held to approach this one, which I. have not included 

 in the analysis above. These are Coccus acutissimus and 

 Paralecanium (Lecanium) expansum. In the former Green 

 could only distinguish two basal segments, but he noticed 

 " lighter transverse marks Avhich suggest an original 

 division into six or seven segments.'' The antennae of 

 Paralecanium {Lecanium) expansum are described as 

 " with incomplete divisions, though a terminal one and a 

 basal two can easily be distinguished." Whether the 

 nymphs of these two species were examined by Green is 

 not definitely stated. But the fact that there were traces 

 of six or seven segments in one and a terminal fourth in 

 the other makes it probable that, at any rate at the time 

 the species were described, the nymphs had six-segmented 

 antennae. And it is improbable that Green would have 

 omitted to examine the nymphs of the only two species 

 in which there is a reduction of antennal segments beyond 

 what he himself gives as the normal number for all nymphs 

 of the family Lecaniinae. 



The reduction from seven to three segments in the 

 Mysore form must therefore be held to be unique. The 

 fact that it is inherited by the nymphs renders no longer 

 tenable the character of a six-segmented antenna in the 

 nymphs as a feature of the genus Lecanium. The Mysore 

 form is therefore entitled to specific rank, and I propose 

 to name it Coccus colemani in honour of Dr. Coleman, as a 

 mark of gratitude for the valuable scientific training I 

 have received at his bands. 



Coccus colemani, sp. n. (Plate V, figs. 2, 3.) 



Adult § characters as in Coccus viridis. But antennae three- 

 segmented, the first and second segments subequal, the third from 

 five to six times the length of the first and having a number of 

 apical and subapical hairs. The dorsal ^ -wise carina not found in 

 any stage. Dermal cells more round than oval, scattered over the 

 derm and from 30 to 80 /x apart- 

 Colour pale lemon-yellow to greenish-yellow. Shape oval, the 

 anterior end being narrower but is liable to variation in specimens 

 fixed on the sides of veins of leaves in which the anterior end is 

 more or less acuminate, and either the right or the left side may be 



