8 2 EXPLANATION OF TERMS 



Mesepimeron: in Odonata; the sclerite between humeral and first lateral 



suture. 

 Mesepisterna: in Odonata; the oblique lateral pieces of mesothorax, meeting 



dorsally in a ridge. 

 Mesially: at or to the middle. 

 Mesinfraepisternum: a sclerite formed between propleuron, mesepisternum, 



mesepimeron and second coxa. 

 Meso: middle: as prefix, drops the O when stem begins with a vowel. 

 Mesoblast: the middle germ layer of the embryo: = mesoderm. 

 Mesoderm: = mesoblast ; gives rise to muscular and circulatory systems. 

 Mesodont: = amphiodont : q. v. 



Mesomeros: the 2d to 5th abdominal segments in Lepidoptera. 

 Meson: the middle plane of the body. 



Mesonotum: the primitively upper surface of the 2d or middle thoracic ring. 

 Mesophragma: an internal prolongation of the metapraescutum, affording at- 

 tachment to some of the wing muscles. 

 Mesopleura: in Diptera, the space before the root of the wing between the 

 dorso- and sternopleural sutures : in Hymenoptera, the piece below the in- 

 sertion of the wings. 

 Mesopleural bristles: in Diptera, are inserted in the angle formed by the 



dorso-pleural and meso-pleural sutures. 

 Mesopleural suture: in Diptera, runs from the root of the wings downward 



and separates the meso-pleura from the pteropleura. 

 Mesopleuron: the lateral surface of the meso-thorax. 

 Mesosternal cavity: in Elateridce, the opening into which the prosternal spine 



or mucro is fitted. 

 Mesosternal epimera: in Coleoptera ; the narrow pieces separating the meso- 

 sternal from the meta-sternal episterna. 

 Mesosternal episterna: Coleoptera; on each side of mesosternum between 



anterior border and epimera : generally separated by a distinct suture. 

 Mesosternal lobes: in Orthoptera; = mesosternellum, q. v. 



Mesosternellum: in Orthoptera, two median lobes of the mesosternum, one on 

 each side of the deep median notch : in general, the sternellum of the 

 mesothorax. 

 Mesosternum: the underside or breast of the meso-thorax. 

 Mesostethidium: = meso-thorax ; q. v. 

 Mesostethium: the middle piece of the underside of meta-thorax, between the 



middle and hind legs. 

 Mesostigma: in Odonata, the spiracles of second thoracic segment. 

 Mesosulcus: a central longitudinal furrow of mesosternum in Hymenoptera. 

 Mesotarsus: the tarsus of the middle leg. 

 Mesothoracotheca: the pupa! covering of the meso-thorax. 

 Mesothorax: the second or middle thoracic ring; bears the middle legs and the 



anterior wings. 

 Mesotergum: = mesonotum ; q. v. 



Meta-: posterior: used as a prefix to designate the third thoracic ring and its 

 parts. 



