CEPHALOPODA. 631 



phalus acetabularis, on account of the number of suckers with which 

 it was beset. In the following year, Cuvier, having received a similar 

 organism which Laurillard had detected in a Cephalopod called Octo- 

 pus granulosus, also believed it to be a parasitic worm, for which he 

 proposed the name of Hectocotylus Octopodis*, assigning the name 

 of Hectocotyliis ArgonautcB to the previously-observed species. 



In 1842 Kolliker|, having detected the same organism, apparently 

 parasitic on the female Argonaut, carefully scrutinised its structure, 

 found that of the skin, with its complex pigment cells, and that of 

 the acetabula, identical with the same parts in the Argonaut : he de- 

 tected, moreover, in a dilated hollow part of the organism, a quantity 

 of spermatozoa, having the characteristic form of those of the Octopod 

 Eledone, and came to the bold conclusion that it was the long-sought- 

 for male of the Argonaut, arrested in its development, and subsisting 

 parasitically on the female, like the diminutive males of the Rotifera, 

 Epizoa, and Cirripedia. It may serve as a wholesome warning 

 against entering upon a scrutiny of parts whilst prepossessed by 

 a foregone conclusion, to remember that the acute and usually 

 accurate observer describes and figures the digestive, circulating and 

 respiratory organs of the same supposed independent individual 

 male animal. 



Verany X first had the good fortune to discover the Hectocotylus, 

 or presumed parasitic male Argonaut, forming one of the arms, sin- 

 gularly modified and developed, of a little Octopod, which he figured 

 under the name of Octopus Caretice. Miiller §, Riippell, and others 

 were not slow in demonstrating that this, or a similarly modified 

 Octopod, was really the male of the Argonauta. 



As in the spiders, which some Cephalopods so singularly resemble 

 in outward form, certain species of the Octopod family have the male 

 apparatus extended into one of the cephalic arms. In the Araneidze 

 the spermatic reservoir of the palp is quite isolated from the testis of 

 the abdomen : in the Octopus granulosus and Argonauta argo the 

 spermatic duct is continued from the testis, which occupies the usual 

 position in the abdomen, into the base of the sexual arm, and opens 

 into a dilated reservoir at the termination of that singularly modified 

 member. It is somewhat longer than the longest of the ordinary or 

 unmodified arms, and is much thicker. The acetabula are larger 

 and more numerous, but retain the arrangement in a double row. 

 The structure of these suckers, and of the skin, resembles that of the 

 homologous parts in the female Cephalopod, as Kolliker most acutely 



* CCLXXVI. Yol. xviii. pi. 11. t CCLXXVII. 



t CCLXXV. § CCLXXIV. 



s s 4 



