54 



strand had begun to form , the eggs emerge from the middle of the wall of the 

 gland, they would be caught between the successive layers of the continuously 

 forming sheet and would be carried away in a spiral row. Finally , if we sup- 

 pose that eggs continue to emerge into the cavity of the oviducal gland for some 

 time after the cessation of its greatest activity , they would not be enclosed 

 between the folds of the completed core , but would lie free in a cavity contain- 

 ing the less dense mucin produced by the gland at the end of the period of activ- 

 ity ; and as the core of the case , with the eggs partially buried in its surface , 

 passes the mouth of the nidamental glands , it probably receives the sheet ot 

 mucin which forms the sheath of the case. The capsule of each egg is probably 

 produced by the oviducal gland. The egg cases are attached in clusters to fixed 

 objects on the bottom and, since a single cluster may contain as many as 175 

 cases and approximately 26,000 eggs , it is probable that several females 

 contribute to the formation of each cluster. The appended table records the size 

 of and number of eggs in three typical egg cases. 



Length of case , m.m 85 70 90 



„ „ stalk „ 15 10 26 



Diameter of case „ 15 7 7 



.. .« STjojIJv ............ O .0 o 



Number of eggs 173 164 158 



Length of eggs m.m 1.5—1.6 



Diameter „ „ 1. —1.2 



Length of egg capsule „ 1.75—1.9 



Diameter „ „ „ 1.6—1.7 



The Vascular System. (Plate I, Fig. 6; Plate II, Figs. 8, 9.) 



The vascular system of the squid is double , closed , and almost perfectly 

 symmetrical. The arterial blood goes out from the systemic heart by either of 

 three aortae, — the anterior (I) the posterior (II) and the genital (III); from 

 these it flows into paired arteries, capillaries and veins. The venous blood from 

 the systemic veins may flow entirely in lateral vessels or for a short time in 

 the median anterior vena cava (VI) or the genital vein (3 5 ). It finally flows from 

 the lateral nephridial vessel (V) into the right and left branchial hearts. The 

 blood from the branchial heart flows through the branchial artery (VIII) to the 

 capillaries of the gill and from them the blood, now arterial, passes thru 

 the branchial vein (IV) to the systemic heart. 



