GLOSSARY. 145 



Thely'tokous (Gr. thelutokos, producing females). A term 



applied to those females in the Insecta which produce only 



female young. 

 The'nar (Gr. thenar, the palm of the hand). The name given 



to the fleshy eminence which forms the ball of the 



thumb. 

 Therapeu'tics (Gr. therapeuo, I cure). The branch of medical 



science which treats of the application of remedies and 



the curing of diseases. 

 Thora'cic (Gr. thorax, a breastplate). Relating to the thorax 



or chest. The ventral fins of Teleostean fishes are said to 



be thoracic in position when they are placed immediately 



behind the pectoral fins. 

 Thora'cica (Gr. thorax, a breastplate). A group of Cirripede 



Crustacea having limbs attached to the thoracic somites, 



while those of the abdomen are only rudimentary. 

 Tho'rax (Gr. thorax, a breastplate). The chest The upper 



division of the trunk in the Vertebrata; the second 



division of the body in the Arthropoda. 

 Thy'mus (Gr. thumos, heart or soul). The name given to a 



gland situate in early life above the base of the heart in 



man and other mammalia, but which wastes with advancing 



age. 

 Thy'ro-hy'al (Gr. thvrtos, a shield; hyoid bone). The name 



given to two ossifications of the hyoid apparatus in the 



lower Vertebrata, which correspond with the great cornua 



of the hyoid bone in man. 

 Thy'ro-hy'oid arch. The third facial arch in the foetus; it 



corresponds with the first true branchial arch of fishes and 



amphibia. 

 Thy'ro-hy'oid membrane. A membrane passing from the 



thyroid cartilage of the larynx to the hyoid bone. 

 Thy'ro-hy'oid muscles. The name given to a pair of muscles 



passing from the thyroid cartilage to the hyoid bone, 

 Thy'roid (Gr. thureos, a shield; eidos, shape). The name 



given to the largest cartilage of the larynx ; also to a 



ductless gland situated upon the front and sides of the 



upper part of the trachea. 

 Thysanop'tera (Gr. thusanos, a tassel ; pteron, a wing). A 



group of small winged insects living chiefly in flowers ; 



called also Physopoda. 

 Thysanu'ra (Gr. thusanos, a tassel; oura, a tail). A family of 



Ametabolous insects. 



