ARGONAUTA ARGO AND THE HECTOCOTYLI. 57 



the appendage about as much more. In an animal of 3 lines 

 long, each part of the Hectocotylus-avm was a few lines shorter. 

 The smallest specimen which I met with measured 2 lines to the 

 base of the arms ; body and appendage of the Hectoco(ylus-arm 

 each 3-4 lines. The length of the uninjured sac was about 

 1 line in an animal of 2 J lines ; on the other hand, it was 3 lines 

 in a specimen whose body, as far as the arms, was 4 lines long*. 



At the thick end of the detached Hectocotyli is the point, 

 where the constricted axis must finally have divided ; it is drawn 

 a little towards the dorsal side, while the h'rst suckers project 

 somewhat forward. No trace of any rent is to be seen, but the 

 surface is quite smooth as if cicatrized, and the fringe which 

 unites the suckers upon their dorsal side is also present between 

 the oblique anterior pair, so that the one series of suckers passes 

 in a continuous curve into the other. 



The point of transition of the thicker body into the filiform 

 appendage is sharply marked in all the free Hectocotyli and in 

 the larger enclosed ones. The suckers with the fringe which 

 unites them cease suddenly, the axis of the body becoming 

 thinner and passing into the appendage. In the smallest speci- 

 men before mentioned, on the other hand, the transition was far 

 more gradual. The suckers in the posterior broad part of the 

 body, which did not measure more than -15 of a line across, be- 

 came gradually smaller and more rudimentary, and finally ap- 

 peared as mere transverse elevations ; when they ceased the dia- 

 meter of the body was still O'l of a line. 



The membranous lobes described by Kolliker at the origin of 

 the suckerless part of the body were present in all free Hectoco- 

 tyli ; but it could generally be clearly observed that there is pro- 

 perly speaking only a single lobe, which in its highest part 

 crosses the body of the appendage transversely, and then passes 

 gradually upon each side into a slight fold. These two folds 

 run along the appendage for a considerable distance : in one 

 case, the most elevated portion of the lobe was prolonged into 

 two elongated processes. The height of the transverse portion 



* An eighth specimen, in which both the body and the unopened sac surpass 

 the above dimensions, is in the possession of M. Verany, who immediately re- 

 collected it on seeing my specimens. It had previously been brought by Krohn 

 from Messina. 



