136 EXPLANATION OF TERMS 



Parabiosis, is where different species of ants form colonies with inosculat- 

 ing galleries, and have their households strangely intermingled, hut not 

 blended. 



Phylacobiosis. is the relation existing between ants and Termites, the ants 

 living in the doorways of the Termites and functioning as guards. 



Synclerobiosis, is an association of two species of ants that usually inhabit 

 independent colonies, for purposes that are not clearly understood. 



Trophibiosis, is the relationship between ants on the one hand and aphids, 

 coccids and the like on the other : these species being sought and attended 

 by the ants for their own benefit : see myrmecophily. 



Xenobiosis, is where one species of ant lives as a guest in the nest of 

 another, maintaining its own household, and mingling freely with the host 

 species, the two living on terms of mutual toleration. 



Symbiotic: species that live together in a state of symbiosis. 



Symmetrical: evenly developed on both sides. 



Symmetry: that regular arrangement of organs or parts which is capable of 

 division into similar halves or similar radii. 



Sympathetic nervous system: applied to the nerves and ganglia of the alimen- 

 tary canal and some other viscera which they innervate ; := vagus ; visceral 

 nervous system. 



Symphily: the relation borne to ants by the true guests which inhabit their 

 nests and are fed and tended ; rendering in return some substance or service 

 desired by the ants : see metochy and synechtry. 



Symphyla: a group name for apterous species resembling myriapods in ap- 

 pearance, with functional abdominal legs and the genital openings on the 

 last abdominal segment : regarded by some as connecting forms between 

 insects and myriapods, e. g., Scolopendrella. 



Symphysis: where two sclerites are joined together by a soft membrane, per- 

 mitting a slight motion. 



Synaptera: originally wingless insects without metamorphosis; the Thysanura. 



Synarthrosis: an articulation without motion. 



Syncerebrum: the compound brain of insects. 



Synchronous: happening at the same time. 



Synciput: that portion of the vertex lying between the eyes. 



Syncitium: masses of protoplasm with nuclei, found in ovarian tubes: giving 

 rise to ova, nutritive cells or both. 



Syndesis: that method of articulation where two parts are connected by a 

 membrane which permits of considerable motion between them. 



Synechtry: the relation borne to ants by insects inhabiting their nests in spite 

 of the efforts of the ants to destroy them : see symphily and metochy. 



Synista or Synistata: those Neuropterous insects in which the mouth struc- 

 tures are undeveloped, forming an imperfect tubular structure : see elinguata. 



Synoecy: the relation that exists between ants and those guests that are 

 indifferent to and tolerated by them : = metochy, and see symphily and 

 synecthry. 



Synonym: a name applied to a species or genus that has been previously 

 named and described. 



