284 COLEOPTERA 



process at tlie posterior extremity ; this serves to place the pro- 

 tecting matter in a proper position and to retain it there. The 

 excrement assumes in various species forms so peculiar that they 

 cannot be considered merely incidental. In several species this 

 covering-matter is like lichen. This is the case with DoJlchotoma 

 'palmarum, the larva of which has, in place of the usual fork, a 

 more complex appendage on the back for the purpose of prepar- 

 ing and retaining its peculiar costume. The pupae, too, some- 

 times retain the larval skin. An extremely remarkable pupa of 

 a Cassidid — possibly of the genus AHpidomoiyha — was recently 

 found by Dr. Arthur Willey in K'ew Britain (Fig. 144). The 

 l)ack of the pupa is covered with a complex appendage, so tliat 

 the creature has no resemblance to an Insect ; this appendage is 

 perhaps capable of being moved, or even extended (Fig. 144, A), 

 during life. Whether it may be formed l;)y the retention of 

 portions of the moulted skins of the larva we cannot say with 

 certainty. 



The most remarkable of the Cassidid coverings yet discovered 

 are those formed by certain small beetles of the tropicnl Ameri- 

 can genus roiyhyrasiyis. P. tristis is apparently a common 

 Insect at Bahia, where it lives on a cocoa-palm. The lar\'a is 

 short and broad, and completely covers itself with a very dense 

 coat of fibres, each many times the length of the body, and 

 elaborately curved so as to form a round nest under which the 

 larva lives. On examination it is found that these long threads 

 are all attached to the anal extremity of the Insect, and there 

 seems no alternative to believing that each thread is formed by 

 small pieces of fibre that have passed through the alimentary canal, 

 and are subsequently stuck together, end to end. Tlie process of 

 forming these long fibres, eacli one from 

 scores of pieces of excrement, and giving 

 them the appropriate curve, is tndy remark- 

 a]>le. The fibres nearest to the body of the 

 larva are abruptly curled so as to fit exactly. 

 Fig. 145.— Nest of intes- and make an even surface ; but the outside 



tiually-made filaments oi , i , • Ti.ii 



inuler which the larva ^^^^^ ^^aud Out HI a SOmewluit l^isliy 



oi Por2jiujms2ns tristis fashion. The construction is nnich like that 



of a tiny bird's nest. Seiior Lace rda iu formed 



tlie writer that the larva makes a nest as soon as it is hatched. 



Another ForpJnj rasjns — P. palmariuii- — has been recorded as 



