56 MORPHOLOGY OF INVERTEBRATE TYPES 



reproductive organs. At the anterior end which is the seat of 

 the central nervous system, are two lateral projections, the 

 tentacles, and behind them, on the dorsal surface, two eyes. 

 Between the tentacles is a retractile grasping organ. 

 Integument. The body covering is composed of a single layer 



RC... 



FIG. 12. Transverse section through the skin of Dendroccdum lacteum 

 after Hallez, modified. GL, gland cell; BM, basal membrane; OM, oblique 

 muscles; Hf, longitudinal muscles; RC, rhabdite mother cell; RH, rhabdites; 

 EP, epithelial cells; CM, circular muscles; NC, nerve cells; DVM , dorso- ventral 

 muscles; TM, transverse muscles; P, parenchyma. 



of cilitated epithelial cells lying on a basal membrane. Between 

 the epithelial cells numerous unicellular gland cells are found 

 which secrete slime, together with branches of bipolar nerve cells 

 and little rods or rhabdites which possibly serve as protection 

 and support to the tender epithelium. The rhabdites are pro- 

 duced by special cells in the parenchyma. 

 Muscular system. The muscular system, which forms a real 



