1 24 ML/NSON. [Vol. XV. 



work of tubes covering the whole ventral and dorsal surface of 

 the animal, and, uniting at the extreme borders of the cephalo- 

 thorax, enclose the massive liver and the other internal organs. 



The ovary, whose double nature is evident only from the two 

 terminal oviducts, has a bilateral symmetry ; but this is incom- 

 plete, because of the somewhat irregular anastomoses over the 

 median line. 



The secondary branches, surrounding the adductor muscles 

 and running parallel with the alimentary tract, are compara- 

 tively large. Owing to their relatively thick walls, they 

 maintain more or less uniform dimensions, even when filled 

 with eggs. These being branches of the oviduct, they serve, 

 like the latter, as reservoirs and channels of transmission 

 for the vast number of eggs that are discharged into them by 

 the numerous tertiary branches. This network of tertiary 

 branches {ov.), covering the entire animal outside of the ad- 

 ductor muscles, is the real egg-producing portion of the ovary. 

 A portion of one of these tubes is represented in PI. XIII, 

 Fig. 16, drawn with a camera from living material, taken from 

 a young animal thirteen inches long, including the tail. 



In the adult animal these tubes are usually filled with eggs. 

 Owing to the feeble resistance offered by their thin walls, the 

 eggs in them are not evenly distributed along the lumen, but 

 are often massed together into large masses, causing irregular 

 swellings that obliterate the meshes between the tubes. This 

 gives the ovary a very irregular appearance, as if it were nothing 

 else than a huge mass of eggs covered by a thin membrane. 

 Over and between these large masses of eggs the various stages 

 of new generations of eggs can be seen. 



After the discharge of the eggs this chaotic appearance of 

 the ovary, for the most part, disappears, and most of the irregular 

 sac-like swellings resume the normal dimensions of the ovarian 

 tubes. These now become conspicuous, not only from the 

 shining aspect of their walls, but from the fringes of the vari- 

 ous generations of new eggs that dot their surface. In the 

 adult animals, except such as have recently moulted, the tubes 

 {ov.t.) are never completely collapsed, but contain a larger or 

 smaller number of eggs. These, when not very numerous, are 



