Category: A

Arch of the alveolar process of either jaw (maxillary and mandibular arch).  

The costal arch; the anterior and lateral boundary between the line dividing the thorax and the abdomen.  

Any anatomic structure composed of a series of arches.  

A curved line; a portion of a circle.  

The hemolysin present in spider venom.  

The part of the arachnoidea enclosing the spinal cord.  

The part of the arachnoidea enclosing the brain.  

Arachnoid membrane.  

A class of the Arthropoda, including the spiders, scorpions, ticks, and mites.  

A member of the class Arachnida. The group of creatures encompassing spiders, scorpions, and ticks, commonly referred to as Arachnida.