HARDWICKE'S SCIENCE-GOSSIP. 



107 



in others it had broken, probably through contraction 

 by the heat of the atmosphere, and had left holes. 



In the several accounts of this larva that I had read, 

 in which reference was made to its remarkable habit 

 of supporting over the back canopy-fashion the fasces, 

 these being carried by the two anal or caudal append- 

 ages, I never could realise how this skeleton plat- 

 form might carry such a substance. However, on 

 closely examining the larva?, I soon saw how this pecu- 

 liar feat was accomplished, though anything I had 

 read on the subject never led me to suspect it would 

 be so. The manner in which it is accomplished is 

 thus : — When the first skin is cast, instead of being 

 thrown off altogether, as is usually the case with 

 growing larvae, it is retained upon the two rigid whip- 

 like anal or caudal appendages, and upon its upper 

 surface are subsequently deposited the faeces which 

 agglomerate, the lateral branched spines of the exuviae 

 being well adapted for the support and retention of 

 this substance, which is, or shortly becomes, intensely 

 black in colour. When the second skin is thrown off, 

 it likewise is retained upon the anal appendages, and 

 is attached to the first exuviae on the under side by 

 the cast skin of the two anal appendages, which con- 

 stitutes a compound connecting link not only between 

 these first two exuviae but between each and all of the 

 four that are thrown off before the larva is full-grown ; 

 whilst on the upper surface the mass of faeces, gradually 

 increasing in width and height, agglomerates through- 

 out the entire length of the dorsal covering and 

 protection, which the larva has the power of elevating 

 or depressing : when undisturbed, this covering of 

 exuviae and faeces lies horizontally over the dorsal 

 region of the larva, canopy-fashion, and more or less 

 completely covers and conceals it from view. 



Several of these larvae I secured, and supplied with 

 their food-plant ; and on leaving the country on 

 August 20th, they were shut up in their box, which 

 was not again opened until near the close of Sep- 

 tember. I then found that all of them had entered 

 the pupa-state, had afterwards fully evolved into the 

 imago condition and hatched out, and were now lying 

 dead on the bottom of the box. 



Such were my first few observations and notes on 

 the very singular larva of the tortoise beetle, whilst 

 the desideratum (mentally made) was, further observa- 

 tions thereon. Hence, being again in the same 

 neighbourhood in the summer of 1883, I again 

 searched the thistles in the same spot as before, and 

 in its season found the larva, fed it up, watched its 

 transformations, and made copious notes thereon : 

 these I will give in the order in which they were 

 made, with such additions and modifications as subse- 

 quent study of the habits and structure of the larva, 

 pupa, and imago have enabled me to make. 



August ilt/i, 1883. — This evening, at 5.30 P.M., 

 I observed the full-grown larvae of the tortoise beetle, 

 as well as very small ones, browsing on the leaves of 

 the thistle, at the same place as I observed them two 



years ago about this same date. It was very airy at 

 the time and quite cool, there being alternations of 

 sunshine and cloud. 



I observe that they eat out the parenchyma of the 

 leaf in roundish small patches from both the upper 

 and under surface, leaving the epidermis in most cases 

 intact above or below, as the case may be. The size 

 of these holes is in proportion with the size of the 

 larva, increasing with its growth ; each hole repre- 

 sents a meal, or a course of a meal, and the paren- 

 chyma is eaten out by the larva backwardly towards 

 itself with considerable despatch. When feeding, or 

 at rest, the canopy of exuviae and faeces lies horizon- 

 tally directly over the dorsal region of the larva, but 

 does not touch it, and extends nearly or completely 

 up to the anterior margin of the thorax, being carried 

 upon the two forward-projected anal appendages. 

 The posterior extremity of the body is turned up at 

 right angles to the anterior and much greater portion ; 

 and the anus is at the extremity of the then erect, 

 cylindrical, and telescopic ventral tube, which is of 

 considerable length and situated beneath the posterior 

 margin of the fecal canopy. The faeces are not black 

 when first deposited, but speedily become so ; and 

 they consist of both liquid and firm parts. The 

 ventral tube is projected to an extraordinary length 

 on the passage of the faeces, chiefly by an evagination 

 of it, and is applied to the hinder margin of the 

 gradually widening and thickening fecal canopy, and 

 the fasces there deposited : this tube, which is in two 

 equal portions fitting into each other, and the body 

 telescope-tube-like, is remarkably flexile, adapting 

 itself readily to the form of the parts to which it is 

 applied, being sometimes bent upon itself at right 

 angles, and at others forming the arc of a circle ; and 

 is, sometimes at least, employed by the full-grown 

 larva in pushing off backwardly from the anal or 

 caudal appendages the fecal canopy (which it invari- 

 ably does), prior to laying itself up to assume the 

 pupal condition, and also in pushing forwards upon 

 the anal appendages against those that precede it the 

 new exuvial platform, on the shedding of the exuviae. 



( To be continued. ) 



THE DEVELOPMENT OF THE FRESH- 

 WATER POLYZOA. 



MR. LORD'S note in Science-Gossip (Dec. 

 1887), regarding the development of the fresh- 

 water Polyzoa, leads me to suggest the plan, I have for 

 some years adopted, for finding the habitats of these 

 beautiful animals. To the end of my telescopic col- 

 lecting stick I screw a brass ring about four inches in 

 diameter, to which a very fine cambric net is sown. 

 This net, drawn through the water several times, will 

 secure a concentrated compound of Rotifers, stato- 

 blasts of Polyzoa, Volvox, and other organisms too 

 numerous to mention. 



