NO. 1G87. Tin: THORAX Ol' I XSlJCTS—^XODCRAtiS. 541 



If tliei'o is any close relation betwoeii the plates of a ehilopod seg- 

 ment and those of an insect thoracic segment a study of the former 

 would indicate that the trochantin is really a sternal element. In 

 McclHtocepJiaJiix (20) the loAver half of the coxa is surrounded by a 

 large l)ilol)ed lateral subdivision (7";;) of the sternum (*S'). In 

 Scolopocrjj ptops (21) this plate {T)i) is atrophied behind the coxa 

 but articulates with the latter by a special condyle. L'dhoh'nts (22) 

 shows a similar condition, but here the lower end of the trochantin- 

 like plate {Tn) is overlapiDed by what is the median division of the 

 stei-num in J/crisforcp/ialiis. Verhoet^' (100.'^)) calls this plate in the 

 Chilopoda the "trochantin." It is absent in Cevmatia (23). Bcirner 

 (190'>) regards the trochantin as a " sternales schniirstiick " and not 

 as a pleural plate. 



Audouin (182-1:) first specifically applied the term ""trochantin" 

 to the plate in Bifpresfis r/if/as which intervenes between the " epi- 

 merum " and the coxa. It happens, however, that in Buprc.stis the 

 episternum presents a number of subdivisions, and Amlouin must 

 have included the posterior of these with the epimerum, thus r(>fer- 

 ring to the trochantin as articulating the " epimerum " with the coxa. 

 (See Biiprexth (/nile/ifa, 100, 7'y/.) It Avill be evident, however, that 

 the plate called " trochantin " by Audouin in Biiprest'iH is the plate 

 which in this paper is identified as such in all the orders where it 

 occurs. 



Verhoetf (11)03) designates as the trochantin the sclerite lying 

 before the coxa and carrying its ventral articulation. 



Comstock and Koclii (1002), as already stated, define as the 

 "trochantin," in the Blattida?, a plate whicji is oidy a part of the 

 entire trochantin, since it does not carry the ventral coxal articula- 

 tion. The subdivision of the trochantin bearing the latter is the 

 "second antecoxal piece" of Comstock and Kochi. 



Comstock and Kellogg (1002) describe the trochantin as a plate 

 " considered to be an appendage of the coxa between the coxa and 

 the antecoxal piece." 



Packard (1800) defines the trochantin as a posterior division of 

 the coxa attached to the epimerum. lie refers to the " coxa meron " 

 of Walton (1000) in the Neuroptera, Trichoptera, and Lepidoptera, 

 which is not the trochantin at all, but a subdivision of the epimerum 

 fused with the hind edge of the coxa. 



The writer agrees with Verhoeff (1903) in his conception of the 

 trochantin, because this appears to agree wdth Audouin's original 

 use of the term. 



Sometimes small additional plates occur between the trochantin 

 and the coxa. These may be called accessory trochantinal or accessory 

 coxal sclerites, according as they are associated more with the troc- 

 hantin or the coxa (9-1, 94, 98, 100, Tfia, Gxa). 



