53 



section each gland is triangular. Its inner surface is adherent to the corre- 

 sponding surface of the other gland ; its upper surface is attached to the visceral 

 mass and its lower surface faces the mantle cavity. The flattened longitudinal 

 lumen extends from the lower inner angle of each gland to its upper surface 

 near its outer angle and divides each gland into two approximately equal and 

 similar segments. 



The accessory nidamental glands are small , oval, light-brown masses mottled 

 with brick red , which lie on each side of the base of the rectum in front of 

 the nidamental glands. The function of these glands is unknown , but it is 

 believed that they contribute to the formation of the egg cases. 



The ova are probably fertilized within the cavity of the oviducal gland, the 

 sperm having entered the mantle cavity with the respiratory water. Vialleton, 

 however , believes that the sperm enter the egg case as , emerging from the 

 siphon, it passes between the bases of the fifth arms and over the buccal pit. 



The eggs are deposited in elongated gelatinous cases which contain from 50 

 to 200 eggs, each invested by a spherical capsule. The material of the cases 

 has been found by von Furth to be similar to the pseudomucins found in ovarian 

 cysts. Each case is attached by a moderately short stalk , which is prolonged 

 into the body of the case as a tapering core and which is also continuous with 

 the sheath of the case. The stalk and core are formed of a sheet of mucin 

 which is wound in a left-handed spiral. Its outer edge is more loosely wound 

 and stretches obliquely from the core to the sheath of the case , enclosing be- 

 tween its successive turns a single row of eggs. The eggs of this closely wound 

 spiral are separated at irregular distances at the base of the case, but towards 

 its middle they are spaced at regular intervals so that they almost form longi- 

 tudinal as well as oblique rows. There are seven or eight eggs in each of the 

 15 to 20 turns of the row, there being in all 150 to 200 eggs in a well devel- 

 oped case. The core ends about one fourth the length of the case from its 

 distal end and consequently the eggs beyond this point are irregularly crowded 

 together at the end of the case. The extent and perfection of the spiral core 

 varies considerably even in the cases of a single cluster and its existence has 

 not , we believe , been noticed previously. 



The structure of the egg case suggests something of its manner of formation 

 which has not been understood. The unfertilized eggs enter the lenticular cavity 

 of the oviduct from the middle of its outer side , and , if the secretion of the 

 gland commences some time before they begin to enter this cavity and if the 

 cilia upon the edges of the lamellae of the gland strike outward and to the left, 

 the secretion would be rolled into a solid strand. Furthermore, if after such a 



