368 T. B. ROSSETER ON THE ANATOMY OF DICRANOT^NIA COROh^ULA, 



Transverse sections show that this organ is embedded in an 

 elongated cavity of the parenchymatous tissue of the segments. 

 The efferent pore is situated in the centre of the distal section on 

 the ventral side. The efferent duct is much swollen at its base ; 

 it runs obliquely, proximally, across the receptaculum, and then, 

 descends horizontally to form the fructifying canal (Figs. 5 b, 

 15 and 16 q), finally entering the shell-gland. In its descent the 

 oviducts, one on either side, attach themselves to it. 



The ovaries (Fig. 5 b r^, r^) are paired organs, and are 

 situated ventrally, one being porose and the other aporose. 

 They occupy about one-seventh of the whole length of the segment, 

 and the dorsal and ventral nerves may be taken as the lateral 

 boundaries of the zone of their development. Each 6vary has 

 its distinctive characteristics. The porose is somewhat oval, its 

 length being 0*236 mm. and breadth O'lOl mm. ; whilst the 

 aporose is pyriform, its length from base to apex being 

 0'219 mm., and greatest breadth 0*135 mm. Each ovary is 

 composed of a number of secretive glands, or lobes, whose ducts 

 lead to one common funnel-shaped sinuous efferent duct. Each 

 oviduct forms a junction with, and on either side of, th& 

 fructifying canal, into which the ova are poured. They are 

 there impregnated^ in their descent to the shell-gland, by the- 

 descending spermatozoa from the receptaculum. 



The yelk-gland (Fig. 5 b i) is situated in the centre of the- 

 proglottis, on the ventral posterior margin, and is ventral to 

 the distal lobe of the receptaculum, which from the dorsal side 

 of the segment partially covers it. In its early stage of develop- 

 ment it is a flattened, oval, disintegrated gland, but it becomes 

 a dense, dark, granulous, reniform body, from the centre of which,, 

 in an upward direction, proceeds the yelk-duct to the shell-gland. 

 The dark granules are nucleated yelk-cells, and as the gland 

 w^astes away by the using up of these plastic cells, it becomes 

 sub-globose, and finally is totally obliterated. It is 0*125 mm. to 

 0*179 mm. long, and 0*067 mm. to 0*111 mm. wude. 



The shell-gland (Fig. 5 b s) is partially covered, at its base, on 

 the ventral side of the segment, by the yelk-gland. It consists 

 of 7 — 8 aggregated club-shaped glands, each one filled with 

 nucleated shell-gland cells, having a diameter of 0*004 to 006 mm. 

 The asci are very irregular in their formation, varying in 

 diameter at the distal end from 0*076 to 0*096 mm. Each of 



