144 Mr. K. Kunhi Kannan on 



have indicated are in individuals. In a mutating species, 

 especially when it is found all over the world, there must 

 be well-marked varieties, and this is what we find. Apart 

 from the " phytophagous " varieties, which are very 

 numerous in Mysore, there are others of a more permanent 

 character. The form of Pulvinaria psidii in the Philip- 

 pines has been given subspecific rank by Cockerell under 

 the name philippina. He says in his monograph on 

 " Coccidae from the Philippine Islands " (Putman Me- 

 morial Fund, 1905), " the long tibia, long third antennal 

 joint, marginal hairs, long bristles on joints 2 and 5 of 

 antennae, etc., all show this insect to be very close to 

 Pulvinaria ficus (Hempel) and P. psidii (Maskell). The 

 six-jointed antennae are distinctive, but may not be con- 

 stant. It is evidently reasonable to treat this insect as 

 a subspecies of psidii, and so far as I can make out P. ficus 

 should stand as P. psidii ficus." That is to say, there are 

 two well-marked subspecies in P. psidii. With regard to 

 a third species, P. cupanae, Green says that it is doubtfully 

 distinct from P. psidii. 



A more striking evidence of the consanguinity of the 

 various types I have dealt with is the variability of the 

 anal plates in all of them. Green says in his introduction 

 to the family Lecaniinae that their form and size afford 

 good specific characters. These characters do not vary 

 with the size of the individual, but are practically constant 

 for each of the several stages, and on p. 236, in describing 

 the variety " quadrat u»i " of Lecanium expansum, he says, 

 " the size and form of the anal scales of the adult female 

 are usually so constant in any one species of Lecanium that 

 such a marked difference as is found in the present instance 

 must be looked upon as varietal." Green has recorded 

 the variability of the anal plates in P. psidii and given 

 drawings of the various shapes they assume. The quota- 

 tions above indicate that this variability is an indication 

 of great instability. Now in the types which I regard as 

 derivatives of P. psidii it is not alone that the anal plates 

 arc of the same shape when normal, but the variations 

 when they occur are more or less in the same direction. 

 They are more fixed in the more stable forms as Coccus 

 viridis, less fixed in Coccus colemani, and least in the 

 forms from Java. The shape of the anal plates and their 

 variability in the same direction is quite ('(insistent with 

 the hypothesis I have advanced of a common origin. 



