LARVAL AND PUPAL STAGES, MYZORHYNCHUS BANCROPTI. 169 



exuvise and an entire specimen, all dehydrated through the 

 graduated alcohols and prepared as permanent microscopic 

 mounts in Canada balsam. It might be added that very little 

 variation was noticed in these three specimens and the 

 characteristics to be noted present a striking constancy. 



Length of larva exclusive of caudal chsetse, 7 mm. 



Head and anal segment dark and heavily pigmented. 



Head. — Head markedly narrower than thorax, mahogany 

 coloured. Eyes roughly triangular in shape, existing merely 

 as aggregations of undifferentiated pigment cells. Antennae 

 slightly curved, covered with many sharply pointed but simple 

 spines the size of which latter decreases from base to apex. 

 Proximal portion of antennae slightly incrassated. A branched 

 seta arises from a submedian point on the antenna, the branches 

 being about 12 in number, of equal length and giving the 

 appearance of a radial grouping. Each antenna is tipped with 

 two stout spinelike processes, weakly chitinised, also with an 

 extremely dehcate branched seta of about five branches. 

 Mouth- brushes consisting of moderately chitinised simple 

 " hairs." Labrum clothed with minute slightly recurved and 

 distally serrated setae. Mandibles consisting of small but 

 heavily chitinised " teeth." Labial plate roughly triangular, 

 the base obtusely and symmetrically crenated ; there are 

 about three lateral, more or less irregular blunt teeth and a 

 median (apical) one of average size. An asymmetrically shaped 

 hole occurs on either side of the median line of the labial plate. 

 The. frontal " hairs " of the head exist as six well-defined 

 branched setae. 



Thorax showing the usual divisions, rendered manifest 

 by the pro-, meso-, and meta-thoracic branched setae, the 

 metathoracic tufts being the most defined and outstanding. 

 In addition to this usual chaetotaxic grouping, there is a group 

 of three long simple hairs which arises from a moderately 

 chitinised tubercle on the antero -lateral margins of the 

 thorax ; at the base of each of these hair-tufts are two unequal 

 spines, one markedly chitinised, the other (longer one) weakly 

 so. On the inner side of these hair-tufts are two minute, 

 branched setae, one on each side of the median line. There is 

 a small but pronounced feathered hair on each side of the 

 mesothorax and a smaller and less- pronounced one on the 

 antero-lateral aspect of the prothorax. Several very minute 

 palmate hairs are to be found on the thorax. 



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