224 AUGUSTA UUCKER. 



this endoskeleton, wliich lies in the cephalothoracic region 

 between the nerve chain below and the stomach above. This 

 organ, which is easily overlooked in K. wheeleri, has not 

 been described for that species, but it has already been 

 observed in K. mirabilis and represented in section by Mr. 

 Borner. In K. florencio3 the endosternite comes out per- 

 fectly into view while a specimen is being treated with KOH. 

 In K. wheeleri this is not the case, and unless one is on the 

 sharp look-out it entirely escapes the notice, so readily does it 

 dissolve away on the use of KOH, along with the surround- 

 ing muscle and nervous tissue. In K. florenci^ the endo- 

 sternite is a V-shaped continuous plate, slightly swollen at 

 the sides in the region between the fifth appendages. Pos- 

 terior to these swellings, and more medianly situated, are two 

 large triangular perforations, which may be said to divide the 

 plate into two regions, an anterior U-shaped portion and a 

 posterior V-shaped portion, which contains the above-men- 

 tioned perforations. Near the anterior limits of the arms of 

 the U are two pairs of small oval apertures, while in the 

 outermost edge of the base of the U are three oval apertures 

 on either side. The attachment of the muscles of the endo- 

 sternite I did not attempt to make out. Fig. 15 of the plate 

 will make much clearer than descriptions can the structure 

 of the endosternite. 



Systematic. — Following the discoveries made by Dr. 

 Silvestri of two species of Koenenia in South America, and by 

 Dr. Mortensen on the island of Koh Chang, in the Bay of 

 Siam, of two other species, comes the new North American 

 and North Texan Koenenia, which makes it seem all the more 

 probable that the hitherto rare order is well represented over 

 the globe. That one of the South American species — 

 K. chilensis, Hansen — possesses lung-sacs, while the other 

 — K. grassi, Silvestri — does not, and that the same con- 

 dition occurs in the case of the two North American species 

 — K. wheeleri possessing lung-sacs, while K. florencia} 

 does not^ — is a point of great interest which invites further 



