1866] 271 



lengthening the 2nd joint and suppressing the 3rd. At what period of 

 the insect's life this adaptation occurred, and what were the circum- 

 stances inducing it, are the points for investigation. 



The species of Lygmna in which the peculiarity has been observed 

 are Calyptonotus pini, O. pedestris, ScolopostetJius pictus, S. adjunctus, S. 

 affinis, 8. contractus, Peritreclms luniger, Drymus sylvaticiis, D. pilijjes, 

 Rhyparochromus dilatatus, R. prcetextatus, R. antennafus, Hypnophilus 

 micropterus, Stygnocoris sahulosm, Nysius thymi, and IscJmodemua 

 sahuleti. 



Tlie aberration probably occurs in other species of this section, 

 but I am not aware that it has been recorded of any before.* In other 

 sections it is rarely seen ; indeed I have only observed it in one indi- 

 vidual of Alydus calcaratus {Goreind) ; but an analogous difference of 

 structure sometimes occurs in the section Seutatina, where, in single 

 specimens of the following species, — Seliirus hicolor, S. alhomarginatus, 

 Tropicoris rufipes, — one antenna has but 4 instead of 5 joints ; the 

 normal 4th being suppressed, the 3rd elongated, and the terminal one 

 of the proper form and size or even lengthened, joined to it ; the entire 

 organ, nevertheless, is shorter than its fellow. 



In the three sections mentioned another kind of irregularity in the 

 formation of the antennae sometimes happens, as I have observed in 

 single instances. Here one of the antennae has one joint less than its 

 fellow, but it is the ordinary terminal one that is wanting, and the one 

 that does duty for it has not assumed its form. In a Tropicoris rufipes 

 {Seutatina) the 3rd joint is shortened and thickened, the 4th much 

 elongated and somewhat thickened. In a Syromastes marginatus 

 (Coreiwa), the 3rd joint is slightly lengthened and thickened towards 

 the end. In a Gastrodes ferrugineus (Lygceina) the 2nd and 3rd joints 

 are both elongated and thickened. 



I have seen two examples of malformation of another kind, each 

 pertaining only to one antenna. In an Enoplops scaplia the first two 

 joints of the left antenna are of the usual form and size, but the 3rd is 

 extremely short, and the 4th, instead of having a slender base, is 

 abruptly anchylosed with the 3rd, so that the junction of the two is not 

 perceptible ; the 4th is also shorter and smaller than usual, and the 

 apex is obtusely rounded. In a Plinthisus hrevipennis the left antenna 

 is very short, the 2nd joint of it is shortened and abruptly clavate at 

 the apex, which is somewhat distorted, and to it is anchylosed one 

 stout, almost cylindrical joint, instead of two each with a fine base, as 

 in the other antenna. 



• Except by Mr. Bold In Scolopoitcthut offinit. (See ante, p. 2li7.) 



