112 Prof. J. Steenstrup on \\ectocoty\\x^-formation 



many of these figures represent males, whilst the arms are given 

 as symmetrical. Amongst the Decapoda, however, a case often 

 occurs, which may have led to an erroneous conception of the 

 symmetrical development, namely that considerable portions of 

 the suckers of the arms, and especially towards their apices, 

 appear as if bitten off during the powerful movements and exer- 

 tions of the animal when it finds itself captured or in great 

 danger ; and that the metamorphosed, papilliferous part of the 

 arm in a Loligo or a Sepioteuthis might easily be confounded 

 with such parts deprived of their suckers, at least on a rather 

 superficial examination*. 



The preceding assertions must only be understood in reference 

 to the existence of this peculiarity, and it must be borne in mind 

 that it was much better known at a period of high antiquity. 

 That Aristotle, and perhaps Pliny, were better informed by the 

 fishermen of the Mediterranean, as to a peculiar arm in the 

 genus Octopus, I have already pointed out under that genus, 

 and at the same time called attention to the fact that Aristotle 

 knew for what purpose this arm was employed. 



As the question so easily arises, how early in the life of the 

 animal this transfer of the arm into the service of reproduction 

 occurs, and how far it remains constantly in the same condition, 

 or perhaps undergoes changes at the season of propagation, I 

 must add in conclusion, that the numerous specimens which I 

 have examined with this view have given me no inducement to 

 suppose that any alteration takes place according to the season 

 of the year or the age of the animal. Even my smallest speci- 

 mens of a species exhibit the same characters as the largest, and 

 I find myself compelled to assume that the male young of the 

 different genera and species quit the egg already furnished with 

 the hectocotylized arm which belongs to them by virtue of their 

 genus or species. As an adherent of the theory that the sex is 

 not subsequently developed, but that it is present originally 

 from the first movements in the egg, I should have preferred 

 being able to ascertain by direct observations that the young of 

 the Cephalopoda quit the egg with their external sexual charac- 

 ters; but I have only had the opportunity of examining the 



* In Loligo, as well as in Ommatostrephes and Onychoteuthis, I have 

 found the cavity of the mouth and the cesophagus filled with aeetahula and 

 horny rings or hooks, evidently belonging to the same animal, and the 

 place of which on the arras could still be determined. From this we see 

 that we must be very cautious in stating that the Cephalopoda serve as the 

 food of these animals because single horny rings or hooks of this kind are 

 found in their stomachs ; but if fragments of the beak, of the gladius, and 

 the lenses of the eyes are found, as has often been done by me in certain 

 forms, no such misinterpretation can take place. 



