HARDWICKE'S SCIENCE-GOSSIP. 



171 



harmonious whole. With a real love for science, 

 as doubtless some of these collectors have, one 

 is sorry to see so much time and money wasted on 

 a pursuit which in their hands yields no fruit of 

 any worth. The wort of the sheer collector can 

 only be classed with that of the compiler of a 

 stamp-album. Whereas, collections of natural 

 objects combined with intelligent study, are invalu- 

 able and almost indispensable to the naturalist. 



I have said this much with the view of trying to 

 persuade some reader of Science-Gossip to take 

 up with osteological research. More workers are 

 what are needed ; and I can assure any one who makes 

 the attempt that he will feel himself amply rewarded 

 for any labour he may undergo by the many pleasures 

 which the pursuit cannot fail to result in. 



THE ANATOMY OF THE LARVA OE THE 

 CRANE-ELY {continued). 



IN the January number of this periodical I de- 

 scribed such portions of the anatomy of the above 

 insect as I had then been able to make out. 

 I purpose now to complete my work so far as the 

 larva is concerned, by describing in order the mus- 

 cular, respiratory, circulatory, and nervous systems, 

 and those curious structures which Mr. Lowne 

 speaks of as being'first observed by Dr. Weismann 

 in Germany, and called by him imaginal discs ; 

 and from which the head and thorax of the future 

 fly are developed. 



If the larva be opened by an incision down the 

 centre of the back, the integuments pinned back, 

 and the viscera removed, the muscles which clothe 

 the inner surface of the skin will be exposed, and 

 will be seen to consist of the following series lying 

 parallel to and on each side of the ventral nervous 

 cord, which occupies the centre of the prepara- 

 tion : — 



1st, a narrow series of longitudinal muscles 

 joining segment to segment, flanked successively 

 by the following broader ones; viz., 2nd, a diagonal 

 series of slightly-crossing muscles ; 3rd, another 

 longitudinal series; 4th, a combined longitudinal 

 and transverse series, underlying the lateral bands 

 of the integument ; 5th, a third longitudinal series 

 adjacent to the dorsal vessel. These divisions are 

 very marked in the abdominal segments, but in the 

 first three, or thoracic ones, the distinction is not 

 clear. With regard to the fourth series, I tlink that 

 the simultaneous contraction of the longitudinal 

 and relaxation of the transverse muscles is chiefly 

 instrumental in producing that swollen contracted 

 condition which I have before alluded to, and 

 for the assumption of which the structural arrange- 

 ment of the overlying portions of the integument 

 seems specially calculated to provide. I must not 



forget to mention that these muscles are, in general, 

 two deep ; consequently the superficial layer only is 

 shown in the drawing, the deeper one (by which I 

 mean that nearer to the skin) corresponds, however, 

 in its general arrangement with that shown. 



In addition to these there are other special 

 muscles proper to the body (exclusive of those 

 which, as forming the outer coat of the viscera, have 

 been already described while treating of these 

 organs) ; viz., 1st, a pair of long, thin muscles 

 connecting the seventh and eighth and ninth seg- 

 ments, which lie one on each side of the dorsal 

 vessel, and have broadened extremities ; they are, 

 I think, the means whereby the looped form which the 

 creature sometimes suddenly assumes when handled 

 is produced ; 2nd, a pair of suspensory muscles, which 

 arise near the junction of the third and fourth 

 segments of the body, and are inserted on the lower 

 part of the stomach ; and, 3rd, another pair of 

 a similar character, arising near the former, and 

 inserted at the upper portion of the proventriculus. 



The muscles of the head differ much in character 

 from those of the body, for whilst the latter are 

 nearly always attached to the integument at 

 both ends, and are more or less of a uniform size 

 throughout, the former are generally attached 

 directly to the integument by one end only, and 

 that by a broad, flat origin, from which they 

 taper to their points of insertion, most frequently 

 in internal processes connected with the movable 

 organs of the mouth. The largest of these are 

 the flexor muscles of the mandibles, which oc- 

 cupy a considerable portion of the cavity of the 

 head, from the internal surface of which they take 

 their origin : they are inserted in two broad, thin 

 processes, connected with a projection on the inner 

 side of the base of the mandible, and consist of 

 six separate muscles, three inserted on the upper, 

 and three on the lower surface of the process. 

 External to these are the extensor muscles ; they 

 are much smaller than the flexors, and are inserted 

 in a slender process outside the points of support 

 upon which the mandible turns ; their action is thus 

 to draw these organs apart. Close beside these are 

 other smaller muscles connected with the maxillae. 



The labrum has a single pair of small parallel 

 muscles, which lie one on each side of the upper 

 internal surface of the head. The labium has two 

 pairs of muscles ; one inserted into a pair of stout 

 processes which bend upwards from the base of the 

 mentum, and partially inclose the mouth, and 

 another into a more slender pair, which are con- 

 nected likewise with the mentum, but beneath. 

 Both these pairs arise from the back of the head, 

 and, I think, act respectively the part of levators 

 and depressors of the mentum, the one raising that 

 organ towards the labrum, and the other having 

 a contrary effect. 



The muscles of the head which are not connected. 



