STRATIOMYS. 15 



alternately to the right and left, contracting itself into the form 

 of the letter S, and then extending itself again into a straight 

 line : by these alternate movements it makes its way slowly in the 

 water. It has much resemblance to some of the Polypi vagi- 

 nati. The last joint of the pupa retains the exact form of the 

 larva-body, is extremely long, and terminates in an orifice to 

 receive the air, which is surrounded by a circle of about thirty 

 diverging rays, consisting of beautifully feathered hairs or plumes. 

 The feathery hairs are so prepared as to repel the water, and 

 thus to suspend the animal by its tail at the surface, and preserve 

 a constant access of air. When it has occasion to sink, it turns 

 these hairs in and shuts the orifice, carrying down with it an air- 

 bubble that shines like quicksilver, and, as is conjectured, enables 

 it again to become buoyant when it wants to breathe. The 

 dorsal vessel (series of hearts, or artery) is attenuated at both 

 ends. The ovaries of the fly are agglomerate, and the egg-tubes 

 form two bundles, in which the branches are not discernible. 



a. First joint of the antennae more than six times the length of the 



second. Species 1. 

 a a. First joint of the antennae about four times the length of the 



second. Species 2-4. 

 a a a. First joint of the antennae more than twice the length of the 



second. Species 5-7. 

 a a a a. First joint of the antennae rather longer than the second. 



Species 8-14. 



1. longicornis, Spl. e. c. 999 (1763). strigata, Fb. ; Shr. ; Gm. ; 

 LI. ; Pz. fn. ! xii. 20 ; Mg. ; Mq. ; Ztt. villosa, Mg. nubeculosa, 

 Mg. tJioracica, Fb. Nigra, alis fuscis apice margineque postico 

 cinereis, ventre fulvo-vittato, tibiis basi tarsisque fulvis, tibiis posticis 

 fulvis nigro-cinctis ; Fcem. capite flavo-quadrimaculato. Long. 5-6^- ; 

 alar. 10-13 lin. 



Black. Head and thorax most thickly clothed with ferruginous 

 hairs : eyes very thickly clothed with black hairs. Proboscis dark 

 brown. Antennae more than twice the length of the head. Scutellum 

 armed with 2 tawny teeth. Wings brown, grey along the hind 

 borders and at the tips. Halteres yellow. Abdomen clothed with 

 hoary hairs on each side, especially towards the base ; underside with 

 4 or 5 pale tawny bands. Tibiae at the base and tarsi tawny ; hind 

 tibiae tawny with a black band. Fern. Head with 4 yellow spots, 2 

 between and 2 behind the eyes. 



Not common. (E.) 



2. Chamaeleon, Dg. ins. vi. 64. 1 (17-52); Fb.; Gf. p.; Ro. 

 etr. ; fig. Sch. ic. i. ix, 3, 4 ; Harris, exp. xi. 1. fig. ; Mg. ; Fin.; Mq, ; 



