408 MR. R. T. LEIPER ON A RECENTLY [Mar. 1 , 



Parenchyma (Plate XXV. figs. 4, 6). 



The parenchyma may be divided into two portions : — (1) A celhi- 

 lar layer, much thicker on the ventral surface than on the dorsal, 

 with oval nuclei lying for the most part at right angles to the 

 cuticle and staining faintly. This is known as the "dermal layer" 

 and gives support to the integument which is immediately super- 

 imposed. (2) Fine protoplasmic strands passing inwards from the 

 dermal portion. These by their anastomosis form a mesh work 

 enclosing vacuoles in which vai-ious free cells lie. On reaching 

 the ovaries they unite to form a delicate capsule, whence still 

 finer strands pass to enclose the individual ova in follicle-like 

 spaces. 



Digestive Vacuole (Plate XXV. figs. 1, 2, 4). 



Immediately over the mouth the ovaries are separated by a 

 large vacuole extending between the dorsal and ventral layers of 

 the dermal parenchyma and traversed by pi'otoplasmic strands only 

 at the periphery. The ovaries soon reunite ventrally, biit the 

 space is continued a short distance further along the mid-dorsum 

 and roughly occupies the anterioi- middle fourth of the body. In 

 it are found particles of ingested material together with wandering 

 cells. It represents the digestive tract, but has not an epithelial 

 lining or any defined passage to the mouth. The food-particles 

 are in all probability caught in the mobile jDrotoplasm pi-esenting 

 at the mouth, and j)assed on into this digestive vacuole. 



Frontal Organ (Plate XXV. fig. 5). 



The frontal organ differs from that of all other Accela save 

 Bohmigia maris-alhi (Sabussow), and is here represented by 

 numerous large single-cell miTCOus glands lying in the paren- 

 chymatous strands and bulging into the vacuolar spaces above 

 and around the brain. Those lying immediately under the dermal 

 parenchym dorsally are perhaps the largest, but their ducts all pass 

 to open like those of the remainder, each by a separate aperture, 

 on to the ventral surface only. As it perforates the cuticle each 

 duct dilates to form a small ampulla. Both glands and ducts 

 stain readily and deeply with h^ematoxylin owing to the presence 

 of very fine granules. The secretion is adhesive and plays an 

 important part in locomotion. 



Nervous System. 



The nervous system, which is not well difierentiated, consists 

 of two lateral masses situated at the anterior end of the body and 

 communicating with one another by a commissure in which lies 

 the otocyst. From each ganglionic mass a lateral and a posterior 

 nerve are seen to be given off. The tissue generally is finely 

 fibrillar, enclosing small clear cells with punctate nuclei. Eye- 

 spots are absent. 



