302 MANUAL OF ZOOLOGY. 



rally possesses an accessory gland ; that of the female secret- 

 ing a viscid material which unites the eggs together, whilst 

 that of the male coats the spermatozoa, and aggregates them 

 into peculiar worm-like filaments, termed " spermatophores," 

 or the " moving filaments of Needham." The spermatophore 

 is filled with spermatozoa, and possesses the power of ex- 

 panding when moistened, rupturing, and expelling the con- 

 tained spermatozoa with considerable force. During the 

 congress of the sexes the male transfers the spermatophores to 

 the pallial chamber of the female, true intromission not being 

 possible. Further, in all the male Cuttle-fishes one of the 

 arms is specially modified to subserve reproduction ; being 

 in many cases so altered as to become useless as a locomotive 

 organ. The arm so affected, in the more striking forms, is 

 said to be " hectoctoylised," and like the metamorphosed 

 palpi of the male spiders it serves to convey the seminal 

 fluid to the female. The mode in which this is effected varies 

 in different species. Thus, in the male Octopus (the Poulpe) 

 the third right arm is primitively developed in a cyst, which 

 ultimately ruptures and liberates the metamorphosed arm, 

 which then appears to be of greater size than the correspond- 

 ing arm on the left side, and to terminate in an oval plate 

 (fig. 1 08). To this terminal plate the spermatophore is pro- 

 bably transmitted, but the arm itself probably remains perma- 

 nently attached to the animal. It is asserted, however, that 

 in the form figured below (Octopus carena) the hectocotylised 

 arm is detached and deposited in the pallial chamber of the 

 female ; being reproduced after each generative act. In Tre- 

 moctopus the third right arm of the male is " hectocotylised," 

 and is converted into a vermiform body, with two rows of 

 ventral suckers, and an oval appendage or sac behind, which 

 contains spermatozoa. Besides the suckers, the anterior part 

 of the back is fringed with a number of so-called " branchial " 

 filaments. 



In the Argonaut the male is not more than an inch in length, 

 is devoid of a shell, and has its third left arm hectocotylised. 

 This arm is developed in a cyst, which is ruptured by the 

 movements of the "hectocotylus," which then appears as a 

 small worm-like body, with a filiform appendage in front, with 

 two rows of alternating suckers, and a dorsal sac with nume- 

 rous " chromatophores." The duct of the testis probably opens 

 into the base of the hectocotylus, which is ultimately detached, 

 and is deposited by the male within the pallial chamber of the 

 female. When first discovered in this position, it was described 

 as a parasitic worm under the name of " Hectocotylus;" sub- 



