The Basal Sclerites of the Leg- in Insects. 11 



Insect Crustacean 



Coxa Coxopodite 



Trochanter Basipodite 



Femur First segment of endopodite 



Tibia Second segment of endopodite 



Tarsus Remainder of endopodite 



Since Henneguy believes that the coxa of an insect is homologous 

 with the coxopodite of a crustacean, he maintains that the styli, or 

 appendages borne on the meso- and metathoracic coxae of Machilis 

 (Fig. 18), correspond to the epipodite (i. e. the appendage of the 

 coxopodite) of the Crustacea. Hansen, 1893, however, together with 

 JouEDAiN, 1888, and Wood-Mason, 1879, considers that the styli 

 represent the exopodite of the Crustacea. Haase, 1889, regards the 

 styli as cuticular appendages belonging in the same category with 

 the tibial spurs, and other cuticular appendages. Banks, 1893, is 

 of the opinion that the styli represent the vestigeal legs of a second 

 subsegment which enters into the composition of the typical thoracic 

 segment; but this view is entirely fanciful, and the same may be 

 said of those theories in Avhich it is maintained that the abdominal 

 styli represent vestigeal legs. A comparison of the parts of an 

 insect's leg, with those of the legs of other arthropods, has been 

 made by Boernee, Grünbeeg, Silvestei, IVeehoeff, and WAiiTON. 

 whose writings are listed in the appended bibliography. 



MiALL & Denny, 1886, have suggested that the trochautin and 

 the pleural sclerites of the roach are "two basal leg joints which 

 have become adherent to the thorax". Heymons, 1889, has likewise 

 come to a somewhat similar conclusion from his study of the em- 

 bryos of certain Hemiptera. Thus, he states that while the epimerou 

 (which he designates as the "pleurit") of the nymph of Nepa, is in 

 no wise connected with the leg region, from the embryological 

 standpoint, the „subcoxa", on the other hand (i. e. the episternum 

 together with the pre-coxal bridge connecting it with the sternum) 

 is in reality the basal portion of the leg. 



In attempting to compare these parts of the thorax of Nepa, 

 with the sclerites of the Blattidae, Heymons comes to some very 

 remarkable conclusions. Thus, he regards the "subcoxa" (i. e. the 

 episternum and the pre-coxal bridge connecting it with the sternum) 

 of the mesothorax of JSFepa, as the representative of both episternum 

 and epimeron of the mesothorax of the Blattidae; and he then comes 



