40 Memoirs of the Indian Museum. [Voi,. Ill, 



peduncle as giant cells — '' cellules jaunes de la pédoncule." The claim of this 

 investigator to have found ovarian cells in the ''male" of Scalpellum peronii 

 (7, p. 121) has been referred to above and will be considered again later. 



Surveying all the stages of development in both the male and the hermaphrodite, 

 the various elements which are found in the peduncle are as follows : — 

 (i) The vesicular spaces of the pupa. 



(2) The rostral duct and the lymph-spaces of the adult. 



(3) The connective tissue cells and fibres. 



(4) The yolk. 



(5) The cement cells and ducts. 



(6) The ovaries. 



(7) The coarsely granular cells of unknown function. 



Before proceeding to consider these elements separately, it would be well to glance 

 at pi. V, fig. 4, which gives a general view of the peduncular region of the pupa of a 

 male. The vesicular spaces [sp.) occur throughout the region. The connective tissue 

 cells are marked f.g. Yolk is marked y. and f.g. The cement cells {r.c.) are chiefly 

 aggregated just above the larval eyes, and the coarsely granular cells {x) occur in the 

 dorsal midline. 



(i) The vesicular spaces of the pupa are always spherical, and it is hardly possible 

 to doubt that they have been distended by some fluid. Their walls are formed 

 by fine membrane or by any of the cellular elements. It is not clear whether they 

 develop into the lymph- spaces of the adolescent and adult or not. 



(2) The rostral duct and the lymph-spaces of the post-pupal stages. — The rostral 

 duct is found in the hermaphrodite from the pupa onward (pi. vi, figs, i, 2, 3) and 

 in a less developed condition in the adult male. In the adult hermaphrodite it 

 extends from the root of the prosoma to the base of the peduncle in the rostral mid- 

 line and lies immediately internal to the muscular wall. At the base of the peduncle 

 it curves inward to the centre of the peduncle and opens out into the network of the 

 lymph-spaces. Small branches also pass off from it throughout the whole of its course. 

 In the young 25 mm. adult its wall is identical in character with that of the lymph- 

 spaces, being formed of delicate membrane with fine connective tissue nuclei. In the 

 adult it acquires a thickened sheath of connective tissue. 



In the male the rostral duct is shorter, reaching only from the root of the prosoma 

 to the upper quarter of the peduncle. 



This system of spaces forms an erectile tissue, by means of which the animal 

 sways to and fro and elongates or shortens its peduncle. 



(3) The connective tissue cells and fibres. — In the pupa, especially in the pupa of 

 the male, the connective tissue cells are often of large size with a considerable mass of 

 protoplasm and a rounded nucleus. In this condition they may also be loaded with 

 yolk-granules, and it is not easy to distinguish them from the cement cells. Their 

 protoplasm, however, does not stain at all with carmine, while that of the cement cells 

 does take up this stain faintly. The more common form of connective tissue cell and 



