38 THE AMERICAN NATURALIST. | [Vor. XXXVI. 
In most insects the antecoxal piece of the mandible coalesces 
with the clypeus, so that the mandible appears to articulate with 
this sclerite. 
In some insects, as Sioned there is a distinct sclerite 
between the mandible and the gena (Fig. 1, 77. This from 
its position on the cephalic side of the base of the mandible 
between the pleural and ventral articulations must be regarded 
as the ¢rochantin of the mandible. 
This completes our account of the sclerites found in the 
external skeleton of the head of the more generalized insects. 
A résumé of the conclusions reached is indicated by the fol- 
lowing table. 
SEGMENTS, SCLERITES, AND APPENDAGES OF THE HEAD.! 








SEGMENTS. ScLERITES. APPENDAGES. 
Vertex and gene. 
L Oéular (Protecerebral).. © |. =... 4. ess 4 Ocular sclerites. 
Front. 
Antennal sclerites. 
II. Antennal (Deutocerebral). «ce OO cQ Sts v.c tenen. 
Clypeus proper. 
III. 2d Antennal (Tritocerebral).| . . . . . . . . . | 2d Antenne of 
Labrum (Mouth). Campodea etal. 
Postgenæ. 
IV. Mandibular. ` Costes. 0 20 7s s T ] MaundIbs. 
 Antecoxal pieces. Trochantin. 
Pharyngeal sclerites. 
V. Superlingual. ‘is wi. c € x » | Operos 
: Maxillary pleurites. 
VI. Maxillary. vta re wo se deN | Mana. 
Lingua. 
Dorsal cervical sclerites. 
VII. Labial. Lateral cervical sclerites. | Labium. 
Ventral cervical scl. (Gsl), | 



pe Š In each section of the middle column the dotted line indicates the division 


EO EE cd iM c E DEE DD t ME 


| 
à 
E 
: 
: 
PE RDUM TIMENS 

