LECTURES ON MOLLUSCA. 159 



direction of the nucleus of the shell, her sail arms still enveloping the 

 frail bark. She generally folds her " oars" together, at arm's length, 

 though she uses them occasionally to direct or assist her movements. 

 What then is her propelling power? She simply breathes herself on, 

 or rather bloivs herself backioards, forcing out the water from her long 

 gill-funnel, and so is carried forward in a contrary direction. She 

 never turns her back on her enemy ; but, on the other hand, she can- 

 not help looking back, wherever she is going. We say il she;" for 

 strange to say, all the paper-sailors turn out to be females. For a 

 long time the lords of the Argonaut creation eluded the anxious search 

 of their brethren of the human species. At last they were found in 

 the form of little stunted octopods, without any shell or sail-arms, 

 not more than an inch long. Let tyrannical husbands see what 

 becomes of their sex in the very highest of the invertebrate animals. 

 The male Argonaut is not known to hold any commimication with 

 his (to him) giant mate, who lives by herself in her palatial shell. 

 The little fellow sends one of his arms, by itself, on the courting 

 errand ; and the lady receives her spouse in the for.m of what was at 

 first regarded as a parasitic leech. M. Koelliker found that what 

 Cuvier had described as the Hectocotylus octopodis, was simply the 

 contents of the left arm of the third pair on the male Argonaut, which 

 is developed abnormally as a colored bag, and periodically gives birth 

 to a Hectocotyle. This having been filled with spermatozoa from the 

 body of the little Argonaut, goes forth on its independent existence, 

 looking like an arm of an octopod ending in a thread. It lays hold on 

 the female Argonaut with its suckers, as though it had a life of its 

 own. It is found on her arms, clinging to her nose, or even inside 

 the gill cavity. It clasps with such strength that it is difficult to 

 detach it ; and yet it has no mouth or other organs for maintaining life. 

 After it has communicated the fecundating influences to the ova, it 

 perishes. It follows that the beautiful paper nautilus is not a true 

 shell, but simply a female appendage to deposit and mature the eggs, 

 and at the same time protect the parent. The newly hatched Argo- 

 naut has no shell ; and is 'said to be shaped like a worm with suckers. 

 This beautiful group belongs only to the existing conditions of our 

 globe. One species alone is found fossil, in the Subappenine tertiaries 

 of Piedmont. It is now living, but not in the Mediterranean, where 

 it is displaced by another species : it has itself migrated to the present- 

 China seas. 



Family Octopodid^e. 



The naked octopods resemble the male Argonaut ; and some (but 

 not all) of them have the same singular degradation of the lordly sex. 

 They generally have small, round bodies without fins, the head and 

 arms being the principal part of the creature. They are seldom gre- 

 garious, but crawl in the neighborhood of the shore, the small species 

 inhabiting pools between tide marks. Here they escape detection by 

 coloring themselves to suit the bottom, and moor themselves to crevices 

 in the rocks awaiting their prey. They are more or less webbed 

 between the arms, like an inverted umbrella ; and progress by flap- 



