482 W. JR. Coe — Anatomy of Cerehratulus lacteiis. 



cells connected both witli the sensory cells and with the nerves.* 

 Directly beneath the epithelium is a thin basement membrane (Plate 

 XV, fig. 1, hm) of amorphous connective tissue with a few large, 

 oval nuclei. In this basement membrane the epithelial cells are 

 imbedded. The epithelial musculature [em) is made up of two thin 

 layers of excessively fine muscular fibres ; an outer circular layer 

 just below the basement membrane and an inner longitudinal layer. 

 These muscles attain their greatest development in the anterior por- 

 tion of the intestinal region, decreasing in thickness towards both 

 ends of the body. 



The cutis consists of muscular fibres and a loose network of 

 connective tissue supporting the tubular glands which are peculiar 

 to this portion of the integument. In the cesophagal region the 

 cutis is made up of an outer, glandular layer (Plate XI, fig. 1, cu') 

 with bundles of longitudinal muscles separated by connective 

 tissue and tubular glands, and an inner layer [cu) of anastomosing 

 radial fibres [rf), longitudinal muscles [hn) and diagonal muscles. 

 Near the head the longitudinal muscle-bundles are widelj" separated 

 by bundles of diagonal muscles. The inner layer disappears near the 

 intestinal region. Around each muscle-bundle is a large amount of 

 connective tissue which forms a framework for the muscle-bundles 

 and for the tubular glands. These glands [tg) are long and closely 

 packed together in the anterior portion of the body but are shorter 

 and less numerous farther back. Each gland is furnished with sev- 

 eral dozens of secreting cells which are closely packed together. No 

 lumen is visible (except when it is filled with secretion), the cells of 

 opposite sides being in contact. The duct to the exterior is slender 

 but may often be traced throughout its length by its deeply stained 

 contents. It apparently exists only at the time of discharging the 

 contents of the cells ; that is, the secretion from these glands is forced 

 between the epithelial cells of the outer layer, where it is often seen 

 in microscopic sections. Each secreting cell is oval or pear-shaped 

 and is usually filled with a deeply stained, granular secretion. The 

 oval nucleus is pushed towards the deeper end of the cell. Each 

 gland is surrounded by a sheath of connective tissue. Perhaps it 

 would be better to speak of these glands as elongated clusters of 

 unicellular glands discharging their secretion through a common 

 duct to the exterior. Numerous radial nerve-fibres pass directly 

 through the cutis and end in the epithelium. 



* In Carinina, liubrecht (7) states that lie finds certain of the epithehal cells to be 

 provided with sensory liairs. 



