82 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. 

 Mesinf raepisternum : 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 sth 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 metaprsescutum, 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 n-,eso-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 Elateridw, the opening into which the prosternal spine 



or mucro is fitted. 

 Mesosternal epitnera: in Colcoptcra ; 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 Orlhoptera; ^ mesosternellum, q. v. 

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

 each side of ihe 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 pupal 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. 



