Rhynehakt — Life- History and Bionomics of the Flax Flea-Beetle. 521 



segment from which they aiise, is, in the opinion of the writer, more 

 expressive. 



MacGillivray's terminology is omitted here, and terms which have become 

 general in descriptions of Coleopterous larvae substituted. Thus, the anterior 

 tergal setae of MacGillivray are here prescutal ; posterior tergal, scutellar, etc. 

 If it is desired to specify individual bristles in detailed descriptions, it is 

 suggested that a system of numbering in conjunction with the naming of 

 groups according to the position they occupy be adopted. Thus prescutal I. 

 would refer to the bristle on the preseutum nearest the dorso-median line ; 

 prescutal II. the bristle next lateral to No. 1, and so on. With such a system, 

 the definite position of any individual bristle would at once be indicated. 



(viii) The '' Frepupa " (PI. XVII, fig. 24). — Prior to pupation the fully fed 

 larva undergoes certain changes whereby the shape materially alters. The 

 body shrinks in strength while the diameter increases ; and, altliough the 

 new form is of a different shape, it is still essentially the last instar, as no moult 

 occurs duiing the shortening process. The length is now from 2'5 to 

 2-8 mm., with an average diameter of I'S mm. The form is cylindrical, and 

 the position usually occupied is with the head and thorax curved strongly 

 ventralwards, thereby giving a characteristic shape (PI. XVII, fig 24). By 

 reason of the developing pupal structures underneath, the outline in the 

 thoracic region is continually changing, and when nearing the last moult the 

 thoracic sternites are pushed out into large protrusions for the accommoda- 

 tion of the developing legs, wings, elytra, etc., of the pupa. These structures 

 can often be seen in suitably prepared -specimens, and the one figured shows 

 the small pads of the elytra as they appeared at that stage. The cuticle of 

 the abdomen is now tough, and the outline of the segments well defined ; the 

 intersegmental spaces appear in cleared preparations as areas traversed by 

 lines or folds, but still show the wart-like tubercles. Many of the bristle- 

 bearing plates are not now separately distinct, but would appear to have 

 become approximated. 



(c) The newly hatched Larva (PL XVI, fig. 9). — This is elongate in form, 

 0'7 mm. long and 0'16 mm. broad (average of six specimens). Body light 

 yellow in colour, with head and posterior end of abdomen dark- grey to black. 

 Three pairs of legs well developed, also anal-proleg. Just after hatching the 

 cuticle is nearly transparent, and the digestive system shows through ; the 

 tracheal system is now seen as fine silvery lines. The eight pairs of 

 abdominal and one pair of thoracic spiracles are fully developed and 

 functional. The head is comparatively large, and measures 0-15 mm. across 

 the epicranial region. It carries the same number of bristles, and shows a 

 similar arrangement of punctures as described for the head of the oldest 



