STUDIES ON THE MOUTH-PARTS OF RHYPA- 



ROBIA MADERI^ (BLATTIDAE) WITH A 



CONSIDERATION OF THE HOMOLOGIES 



EXISTING BETWEEN THE APPENDAGES 



OF THE HEXAPODA^=- 



The question as to the homologies existing among the 

 paired appendages of the Hexapoda has received attention 

 from various investigators, and in particular from Han- 

 sen, Heymons, Borner, Verhoeff, and Escherich, none of 

 whom however have progressed far toward a satisfactory 

 solution of the problem. In general it has been accepted 

 that the stipes and mentum correspond to the thoracic 

 and abdominal coxae while the maxillary and labial palpi 

 were equivalent to the trochanter, femur, etc., or the 

 functional leg. 



Studies on Khyparobia maderice, the giant cockroach 

 from Panama, particularly of 10mm. and 12 mm. em- 

 bryos, as well as other investigations in connection with 

 the appendages of the Thysanura, make it evident that 

 the typical appendage (mouth-parts, thoracic, abdominal, 

 caudal) of the Hexapoda consists of seven definite areas 

 best represented by the maxillae with the galea, lacina, 

 ectostipe!, endostipe, ectocardo, endocardo, and palpus. 

 Furthermore the palpus should be homologized with the 

 stylus of the thoracic and abdominal coxae and not with 

 the functional leg, inasmuch as both palpus and stylus are 

 appendages of homodynamous areas (ectostipe, ecto- 

 mentum, meron) while the leg is an appendage of the 

 area (endocoxa) corresponding to the endostipes. 



The facts noted suggest the origin of the biramose ap- 

 pendage of the Hexapoda directly from the parapodium 

 of the Polychaeta, the notopodium and neuropodium 



^Reprinted from Annals Entomological Society of America, vol. 6 (1913), 

 pp. 132-133. 



