292 



At Rattlesnake Ferry, on the Big Muddy River near Grand Tower, 

 the pupa:^ were very common, and from a log which was floating in the 

 stream, many specimens were obtained by the simple expedient of im- 

 mersing the exposed portion of the log, when the pupae immediately 

 floated off and were readily seen and captured in the water. Many 

 pup?e were also obtained from the surface of a box moored in the 

 river, some specimens being several inches above the water-level. In 

 cases where the author has reared the species it has been observed that 

 the pup?e had no difficulty in making their way up the side of the vials 

 or bottles in which they were kept, and no imago has yet been observed 

 emerging from a pupa which was not at least partly clear of the water. 

 It may be mentioned, however, that in the case of Culicoidcs vari- 

 pennis Coquillett no observations were possible owing to the absence 

 of the author on field work at the time of the emergence of the adult. 

 Several specimens of Palponiyia longipcnnis Loew have been reared in 

 vials in this office, and in all cases the pupae have remained partly sub- 

 merged in the water at the time of emergence of the imago. It is pos- 

 sible that the surface of the glass proved too slippery for this species, 

 though it presented no difficulty to large numbers of pupae of Johann- 

 sciwinyia caudclli Coquillett and /. flaziditla Malloch. 



Imaginal Characters 



The antenna in both sexes in this subfamily are 15-jointed, the 

 last three to five joints in most species being very distinctly elongated; 

 in the male the antennal plumes are long and numerous, in the female 

 short and sparse. Proboscis in most species well developed in the fe- 

 males, less developed in the males ; palpi with four or five joints. 

 Thorax and abdomen in some species with long more or less scalelike 

 hairs, in others with only a few short fine hairs ; hypopygium as in Fig- 

 ures 2 and 7, Plate XIX. Thorax not protruding over head. Legs 

 rather stout, not elongated, their surfaces in some genera with con- 

 spicuous hairs, in others with short black thorns on the ventral surfaces 

 of some or all of the femora, or almost bare; empodium present or ab- 

 sent ; tarsal claws short and equal, or elongated and subequal, or un- 

 equal in length. Wings either with surface hairs, or bare ; venation as 

 in Figures 1-12, Plate XXII. 



The keys here given for species of this subfamily include larvae 

 and pupjc of those species which have been described from North 

 America. Owing to the rather unsatisfactory descriptions of the 

 imagines of most species described from the same area, and to the 

 fact that but few of them occur in the collection before me I have not 

 attempted to give complete keys for imagines of the species of Cera- 



