THE APHIDES OF GUERNSEY. 83 



different genus, and even more, suggested that a new family 

 should be formed for its reception between the Aphidce and 

 the Coccidce. It is simultaneously produced with the normal 

 form, but after a slight growth continues for months without 

 further change, and finally dies Avithout having developed in 

 itself any reproductive organs. In the " Transactions of 

 the Microscopic Society " of 1852, Mr. J. Thornton des- 

 cribed it under the name of Phyllo'pliorus testiidinatus^ a 

 hemipterous insect feeding on the common maple, and he 

 justly considered it as a larva of some indeterminate Aphis. 



Mrs. Lane Clarke also observed the same insect in 1858, 

 and placed it between the families of Aphidce and Coccidce 

 under the name of Chelymorphu testndo. In the year 1862, 

 Yander Hoevan, of Leyden, published another memoir on the 

 same insect, and gave it yet another name, Peripillus testudo. 

 He, like Thornton, regarded it as a larva of some unknown 

 Aphis. Five years later Messrs. Balbiani and Signoret made 

 known the unexpected fact that the common «iaple Aphis has 

 the faculty of producing two sorts of young, one of a normal 

 type, the other diverse in form and incapable of reproducing 

 its kind. According to these authors the green viviparous 

 female of Chaitophori/s aceris contains at the same time two 

 descriptions of embryo. The brown variety has characters 

 much as other Aphides show. At birth they are garnished 

 with tufts of simple hair, and even at this early stage of their 

 existence they exhibit distinct embryonic rudiments of other 

 Aphides within them. (3n the other hand, the bright green 

 variety has a figure and appearance so different, that except 

 it had been seen that the same female produced both forms, 

 we certainly would have referred them to species altogether 

 separate. 



The following is a brief description of this singular form : 

 Form oval, bright green ; eyes dark red or black ; head very 

 broad and large with two shallow lobes on the occiput ; thorax 

 not visibly separated from the head ; abdomen broad, oval ; 

 dorsum and sides decorated with four rows of plates or pseudo 

 scales, which gives the insect a somewhat tesselated appear- 

 ance, and so may be likened to the carapace of a tortoise ; the 

 legs are short and much flattened. But the most remarkable 

 part of the insect is the development of the tegumentary 

 system. Instead of the hairs seen in the normal young, the 

 body and limbs are furnishel with a series of flat transparent 

 leaflets, which surround the front, the abdominal margin, and 

 the outer edges of the tibae. The tarsi, or feet, have in 

 addition to the usual double claw two minute hairs, the sum- 



