GENERAL ANATOMY OF THE SQUID. 349 



VI. The Reproductive Organs of the Male. 



a. Carefully examine the tip of the left ventral arm of 

 a male specimen, — the arm which is marked a"' in Fig. 

 177, and notice that the acetabula are absent, and that 

 their stalks become modified into elongated papillae, which 

 are different in shape from the stalks of the acetabula on 

 the other arms. Examine the tip of the corresponding 

 arm of a female, and notice that it is not difierent from 

 the tips of the other arms. 



The portion of the left ventral arm of the male, which 

 carries the papillae, is a rudimentary hectocotylus^ or copu- 

 lating organ. It does not seem to be a reproductive organ 

 in the squid, although it is fully developed and functional 

 in many other Cephalopods. 



b. The Testis. This is a somewhat flattened, pear- 

 shaped gland (Figs. 180 and 181, m), which lies near the 

 posterior end of the visceral mass, on its dorsal surface. 

 It is enclosed in a thin, transparent, membraneous capsule, 

 and the blind sac of the stomach is on its right side and 

 ventral surface. Its upper surface is irregularly rounded ; 

 its lower end pointed; its ventral surface flattened and 

 slightly concave, and its dorsal surface is convex, and 

 marked by three or four parallel longitudinal ridges, 

 which fit the longitudinal folds of the pen. Notice the 

 genital artery (Fig. 181, ?), which enters the testis on its 

 upper edge, and helps to support it in its capsule. Xotice 

 also that a delicate membrane forms a sort of mesentery, 

 which binds the testis to the dorsal wall of its capsule. 



c. No duct is joined to the testis directly, and the ripe 

 spermatozoa escape from the seminiferous tubules which 

 open near the middle of the ventral surface, and pass into 

 the cavity of the capsule, from which they pass into the 

 excretory duct. 



