Complex sentence: The esophageal glands are small compound racemose glands of the mucous type: they are lodged in the submucous tissue, and each opens upon the surface by a long excretory duct.
Split into simpler sentences: The esophageal glands are small compound racemose exocrine glands of the mucous type. They are lodged in the submucous tissue, and each opens upon the surface by a long excretory duct.