NO. 2242. MORPHOLOGY OF THE 8TREPSIPTERA— PIERCE. 427 



TRIOZOCERA MEXICANA Pierce. 



Plate 65, figs. 1-10. 



Only two specimens of this species occur, the type in the United 

 States National Museum collection and the paratype in the author's 

 private collection at the museum. 



New drawings have been made to illustrate the thoracic characters. 



By the use of improved microscope accessories the mouth parts 

 have been studied. These are very aberrant, the mandibles being 

 reduced to a tiny filament and the maxillae being long pubescent 

 appendages with a small second joint attached before the tip (pi. 65, 

 figs. 4, 5). 



The antennal structure is very rough, consisting of round sensory 

 organs surrounded by setigeroiis tubercles (pi. 65, fig. 3). 



The description of texana will fit this species in general. It is im- 

 portant to note that the author's illustration in Genera Insectorum 

 (pi. 1, fig. 1) was in error as to the shape of the scutellum. The speci- 

 men was mounted slightly on its side and hence not easily studied. 



II. Family MENGENILLIDAE Hofeneder. 



Erratum : Gen. Insect., p. 10, line 2, read " Vol. 32 " for " Vol. 31." 



This family is characterized in addition to the six-jointed, four- 

 branched antennae, and five-jointed tarsi, by an emargination of the 

 head, a metathoracic praescutum placed entirely in front of the 

 scutum and not reaching the lateral angles; a very large meta coxa; 

 and a large postlumbium. 



Table of genera. 



1. Scutum divided by scutellum 2. 



Scutum narrowly connected in front of scutellum Tctrozocera Pierce. 



2. Scutellum broad in front; wings lacking the third anal vein, with two de- 



tached veins between radius and medius and one beliind niedius ; mandi- 

 bles trianguhir Austrostylops Lea. 



Scutellum narrow in front; wings lacking two anal veins, with two detached 

 veuis between radius and medius and one behind medius; mandibles elon- 

 gate, acute MengenUla Hofeneder. 



3. Genus MENGENILLA Hofeneder. 



Errata : Gen. Insect, pp. 10, 11, 16, 29, read " Vol. 32 " for " Vol. 31." 



MENGENILLA CHOBAUTII Hofeneder. 



Plate 66. figs. 6, 7. 



Because of Hofeneder's misinterpretation of the parts of the thorax 

 the writer has made drawings based on the original illustrations to 

 serve as an aid to the proper understanding of the following remarks. 



It is apparent from Hofeneder's drawings that this insect has 



