GLOSSARY. 1 1 



Archego'nium (Gr. archos, chief; gune, a female). The organ 

 which contains the female reproductive elements in 

 cryptogams. 



Archen'tron (Gr. archos, chief; enteron, the intestine). The pri- 

 mitive alimentary sac in the embryo of some of the 

 Invertebrata. 



Archiblas'tula (Gr. qrchos, chief; blastano, to germinate). A 

 term applied by Haeckel to the vesicular morula formed by 

 the process of yelk division in the ovum of the Physemaria. 



Arctis'ea. A group of the Arachnida. 



Arctoi'dea (Gr. arktos^ a bear). A group of the Carnivora 

 which includes the bears, weasles, &c. 



Arctopithe'cini (Gr. arktos, a bear; pitheks, an ape). The mar- 

 mosets, small thickly-furred quadrupedal apes. 



Area germina'tiva (L. germinal area). The area of the ovum 

 in which the embryo appears. 



Area opa'ca (L. opaque area). The marginal opaque ring 

 which surrounds the pellucid area of the ovum, and from 

 which the foetal appendages are developed. 



Area pellu'cida (L. pellucid or clear area). The central por- 

 tion of the germinal area from which alone the embryo is 

 developed. 



Area vasculo'sa (L. vascular area). The area of the blasto- 

 derm in which the foetal blood-vessels are developed. 



Are'olar (L. areola, a little space). Applied to a form of 

 connective tissue which exhibits small spaces between its 

 fibrous felt-work. 



Arreno'tokous (Gr. arren, arrenos, a male ; tokos, a bringing 

 forth). A term applied to those small females amongst 

 insects which lay eggs, from which only male offspring are 

 developed. 



Ar'tery (Gr. aer, air ; tereo, I keep ; or it has been suggested 

 probably Gr. arteria from arter, that by which anything is 

 suspended). A vessel which conveys blood from the 

 heart, and the largest of which (the aorta) helps to suspend 

 the heart. Arteries were thought by the ancients to 

 contain air. 



Arthro'dia (Gr. arthron, a joint). A joint with nearly flat sur- 

 faces, as in the articulations of the carpus, tarsus, and 

 vertebrae, admitting motion on all sides. 



Arthrogas'tra (Gr. arthron, a joint ; gaster, the stomach). The 

 scorpions and pseudo-scorpions, a division of the Arach- 

 nida. 



