Mr. F. Walker's Descriptions of Aphides. 95 



structure with remains of vegetable fibre interspersed through it. 

 It was found to contain nearly forty species of Diatomacea, viz. — 



Eunotiece. Cymbellece. 



Epithemia alpestris. fCymbella Ehrenbergii. 



fE. gibba. C. cuspidata. 



E. ocellata. -fC. helvetica. 



E. proboscidea. fC. maculata. 



E. turgida. fCocconema cymbiforme. 



E, Zebra. Gomphonema minutum. 



fEunotia Monodon. G. pohliaeforme. 



Himantidium Arcus. Naviculece. 



Fragilariece . Navicula attenuata. 



Fragilaria rbabdosoma. t^'^ 5 " ^ 8 / 



N. dicephala. 



Meloseirece. fN. inflata. 



Meloseira Italica. S^*?? 1, 



M. subflexilis ? t N - oblonga. 



. N. radiosa. 



Surirelleai. N> r h omb oides. 



Campylodiscus Clypeus. N. viridis. 



Surirella elliptica. Stauroneis lanceolata. 



S. Solea. Amphora ovalis. 



Synedra capitata. A. elliptica. 



Cocconeidete. Tdbellariece. 



Cocconeis Pediculus. Tabellaria fenestrata. 



Those marked f were most abundant. 



X. — Descriptions of Aphides. By Francis Walker, F.L.S. 



[Continued from p. 48.] 



Eighteenth Group. 



This group may require subdivision, but it does not contain 

 many species. 



33. Aphis Picece. 



Aphis Picece, Panz. Faun. Germ. 78. f. 22; Fabr. Bhyn. 302. 

 56; Zett. Faun. Lapp. i. 557. 1 ; Kalt. Mon. Pflan. i. 141. 111. 



Lachnus grossus, Kalt. Ent. Zeitung, 1846, 175. 



The viviparous winged female. This is black, smooth, and shi- 

 ning : the front of the head is slightly convex : there are two im- 

 pressions on the crown : the feelers are red, filiform, and hardly 

 half the length of the body ; their tips are black ; the fourth joint 

 is rather more than one-third of the length of the third, which is 

 crenulated beneath; the fifth joint is a little longer than the 

 fourth ; the sixth is not half the length of the fifth ; the seventh 

 is extremely short : the eyes are black and prominent : the mouth 



