Japanese Triclaclida Maricola. i n 



as f(jl]<)\vs : in Fr. lactea nearly 1: 3, in St. trigonocephala 1: 6 and 

 in Ect. limuli 1: 4-5. 



So far as m}^ observations go, there exists no essential differ- 

 ence in structural respect; nine layers can be clearly made out, as 

 stated by Böhmig. For the sake of convenience they may now be 

 distinguished into three zones, viz., the outer, the middle and the 

 inner. 



Older Zone. — Externally the thin epithelial plate of the 

 pharynx is, as usual, covered by a ciliary layer which disappears 

 on the lip of the organ, where the ducts of the pharyngeal glands 

 open out. Immediately beneath the epithelial plate is a delicate 

 basement membrane and the musculature consisting of two layers 

 of outer longitudinal and inner circular fibres. Generally the 

 musculature is very well developed near the proximal portion of 

 the pharynx and gradually diminishes in thickness towards the 

 tip of the pharynx. The sets of fibres are much better developed 

 in Ect. limuli than in the other species examined by me. Directly 

 below the circular muscles there occur numerous nuclei which, in 

 my opinion, seem partly to belong to the epithelium, and partly 

 to be remnants of cells producing muscular fibres. 



Middle Zone. — This part consists chiefly of parenchymatous 

 connective tissue traversed lengthwise or crosswise by several 

 elements, such as glandular ducts, nerve plexus and muscular 

 fibres, which predominate generally to an extraordinary degree. 

 Embedded in the parenchyma near the intestinal mouth are 

 numerous pharyngeal glands in which, as is well known, two sorts 

 can be distinguished, viz., the cyanophil and the eosinophil. The 

 latter glands stainable violet with haematoxylin-eosin are abun- 

 dantly distributed somewhat in front of the former which occur in 

 a sparse number close near the pharynx-insertion and take on a 

 deep red colour. These glandular cells vary in form, being usual- 

 ly pyriform. The efferent ducts of the cyanophil glands are 

 formed into a strong compact bundle on entering the pharynx, 

 and they run, immediately beneath the outer zone, the whole 

 length of the pharynx and finally open into the pharyngeal 

 chamber at the tip of the organ. Besides, they send out some fine 



