HELOPHILUS. 249 



rous zigzag folds attached to the terminal tube ; when this issues 

 from the outer tube, they consequently begin to unfold, and when 

 it is entirely disengaged, they are become quite straight and 

 parallel to each other. It is supposed that when the animal has 

 occasion to push forth its respiratory apparatus, it injects into 

 these vessels part of the air contained in the body of the tracheae, 

 which would cause them to unfold and push forth the tube. 

 When this insect assumes the pupa, instead of its anal respiratory 

 organ it has four respiratory horns in the trunk near the head." 

 The species may be thus divided : 



a. Abdomen oval. 



b. Abdomen semitransparent. Antennae black. Species 1-3. 



b b. Abdomen opake. Antennae luteous. Species 4. 

 a a. Abdomen linear. Species 5-7. 



1 . pendulus, L. s. n. ii. 784. 28 (1767) ; Em. ; Schll, ; Schff. ; 

 Dg. ; Fb. ; Shr. ; Gm. ; Gf. ; Pz. ; Mg. ; LI. ; Fin. ; Mq. ; Ztt. ; Lw. 

 similis, Ct. Niger, capitejlavo nigro-vittato, abdomine chalybeoferrugineo- 

 quefasciato lateribusfulvo-maculato. Long. 4-6 ; alar. 8-12 lin. 



Black. Head in front yellow with a black stripe. Fourth joint of 

 the antennae luteous. Thorax with four yellow stripes; scutellum 

 tawny. Wings slightly grey. Halteres yellow. Abdomen with chaly- 

 beous bands along tlie ferruginous hind borders of the segments, and with 

 two large tawny angular spots on each side near the base ; first pair 

 yellow in front, larger than the second, which have two yellow dots 

 between them, and a yellow interrupted band behind them. Femora tawny 

 towards the tips ; tibiae tawny ; tips of the fore tibiae and of the hind 

 tibiae black. 



Generally distributed. (E. S. I.) 



2. hybridus, *Lw. e. z. vii. 141. 5 (1846). Niger, capite fiavo 

 luteo-vittato, abdomine luteo nigro-vittato. Long. 6 ; alar. 11 lin. 



Black. Head in front yellow, with a black stripe. Fourth joint of 

 the antennae luteous. Thorax with four yellow stripes; scutellum 

 ferruginous. Wings colourless. Halteres yellow. Abdomen luteous, 

 with a black dorsal stripe, which is widened at the base and towards the 

 tip, where there is a dingy yellow band, whose hind border is deeply in- 

 dented. Hind femora with an indistinct tawny band on each tip ; an- 

 terior femora luteous towards the tips ; hind tibiae luteous towards the 

 base ; anterior tibiae luteous ; tips of fore femora black ; middle tarsi 

 tawny towards the base. 



Rare. In the collection of the Entomological Club. (E<) 



3. triyittatus, Fb. s. a. 235. 15 (1805); Mg. ; Ztt.; Lw. pen- 

 dulus, Rsi. Niger, capite fiavo luteo-vittato. Long. 7-8 ; alar. 12-14 

 lin. 



VOL. i. 2 K 



