June 2021

1. Eruciform   d. Caterpillar-shaped  
2. Textiform    a. Web-shaped
3. Ensiform     b. Sword-shaped 
4. Sulciform    e. Grooved or depression-shaped   
5. Falciform    c.  Sickle-shaped

The missing number is 15 – Each two-digit number in the middle is the sum of the three digits on either side.