356 Annals Entomological Society of America [Vol. IX, 



suffices to show anyone who will take the pains to make it, 

 that they are strictly respiratory appendages, which may be 

 readily observed in operation in aquaria. These appendages 

 break through the surface film and the hollowed sides being 

 placed in juxtaposition, they form a tube leading air to the 

 spiracles, as already mentioned. These spiracles are larger 

 than the others, and from them lead the two main tracheal 

 tubes lengthways of the body, which connect by side branches 

 with each other and with the functional abdominal spiracles. 

 These spiracles are placed in a pilose stripe, silvery with 

 enmeshed air when the bug is in water, situated on the under 

 side of the abdomen at the connexivum. The thgracic spiracles 

 are also large and functional, but from their structure, size 

 .and position are evidently used for respiration only when the 

 bug is in flight. The nymphal respiratory adaptation is quite 

 different, as the strap-like appendages are absent, the abdomen 

 is totally covered with a long and thick pile, and there are two 

 large spiracles situated under the sternal plates, which are 

 very large and fringed with long hairs. 



The typical, and only, representatives of the anal tube 

 type of aquatic respiration are the Nepidce. This family is 

 extremely peculiar, and its aquatic life offers no criterion to its 

 phylogenetic position. Based on certain structural characters, 

 it has been removed from the Pagiopod Heteroptera to the 

 Trochalopod series by Schjodte, followed by Kirkaldy. This 

 has not been accepted by the European master, O. M. Reuter, 

 but the manner of oviposition, and therefore, the genital 

 characteristics, have been overlooked. These, if at all valid as 

 indications of affinity, confirm the propriety of its removal to 

 the vicinity of the Reduviidce, to certain of which it has indeed 

 a striking superficial resemblance in structure, which is borne 

 out by the appendages of the ovum and by the egg-laying 

 habits, a parallel to which is to be found in Melanolestes abdom- 

 inalis. This predaceous Reduviid, not unfrequently found 

 under stones in fields, inserts its eggs into the earth, leaving at 

 the surface a crown of filaments, which are greater in number 

 but similar in appearance to the seven filaments surmounting 

 the ovum of Nepa. For this reason, it seems best to continue 

 to consider this family as properly placed in the Trochalopoda 

 and near to the Reduviidce, as has been done by Kirkaldy. 



