346 The American Naturalist. [April, 
There are met with in a series of species, dextral as well as sinistral, 
on the concave side, a third group of uncini, representing a fourth 
thoracic setigerous ring that is lacking in others. 
All this shows the influence of the spiral tube, and is explained by 
the movements of the animal. The functional activity of the organs of 
the concave side has preserved them, and is to be taken into account in 
any phylogenetic grouping. 
Taking the direction of the spiral and the presence or absence of the 
thoracic ring into account, it is evident that the genus Spirobis may be 
divided into four subgenera, as follows : 
Dextral species, 
With 3 thoracic rings ; : Dexiospira. 
With 4 thoracic rings : Paradexiospira. 
Sinistral species, 
With 3 thoracic rings ; j Leospira. 
With 4 thoracic rings ‘ Paraleospira. 
The Malpighian Tubes of the Orthoptera. ‘_The malpig- 
hian tubes of the Orthoptera, as regards their number and length, pre- 
sent a great analogy with those of the Hymenoptera, but differ from 
them in their disposition and their mode of opening. 
Among the divers excretory contents of these glands have been found 
in abundance: urate of sodium and urate of calcium in Gryllus; uric 
acid in Gryllotalpa, in the form of irregular spherical or ovoid concre- 
tions or of prismatic crystals ; urate of sodium and uric acid in Blatta 
and Periplaneta. 
Mr. Bordas’ studies embraced some’ forty species of the principal 
families of Orthoptera, and result in the following conclusions: 
In the Forficulide the tubes are few (8-10) and grouped into two 
opposite fascicles. 
In the Phasmids they are very numerous, and united into 20-24 
fascicles (in Phibalosoma), opening into an equal number of hemi- 
spherical or conical tubercles, which are short and are disposed in a 
circle around the intestine, of which they are simply evaginations. In 
Acanthoderus and Necroscia each collecting tubercle receives only two 
or three Malpighian tubes. 
In the Mantidx there are some 60-70 urinal tubes, opening some- 
times irregularly, sometimes in groups of three to four (Eremiaphila). 
The praying mantis possesses 50-60, united into several bundles, sepa- 
rated by narrow free spaces. 
*L. Bordas. Comptes-Rendus, CX XIV (1897), pp. 46-8. 
