152 VERANY AND VOGT ON THE HECTOCOTYLI 



of the females, it is probable that these charged arms creep by 

 the aid of their numerous suckers as far as the aperture of the 

 female generative organs, when the spermatophore then performs 

 its office. 



We sum up then by offering the following conclusions : — 



1. The Argonaut, the Tremoctopus violaceus, and T. Carena, 

 have males whose structure agrees with that of the common 

 Cephalopod-type. 



2. One of the arms of these males becomes specially modified 

 into a copulatory organ. 



3. The beings known at present under the name of Hectocotyli 

 are not separate animals, but are merely the detached copulatory 

 arms of the males, charged with a seminal machine. 



4. The copulatory arms are detached and renewed periodically. 



DESCRIPTION OF THE PLATES. 



[The great number of figures given by MM. Verany and Vogt rendered it 

 requisite to exercise some selection, and to exclude any that were not absolutely 

 necessary. Of their four Plates, the three last (PI. 7, 8, 9, Annales) are exactly 

 copied in our Plates II. III. and IV. ; but only two figures of their first Plate 

 (6, Annates) are given in our Plate I. figs. 3, 4. The others appeared to be 

 not necessary to the comprehension of the memoir. This change has of course 

 rendered requisite a new numbering of the figures.] 



PLATE I. 



Fig. 3. Tremoctopus Carena. Male, seen from the dorsal surface, a, aperture 

 of the retroverted sac which contained the Hectocotylus ; b, vesicle 

 which contained the flabellum ; c, flabellum. 



Fig. 4. Tremoctopus Carena (male), with the vesicle still containing its Hec- 

 tocotylus. 



PLATE II. 



Fig. 1. Male T. Carena, seen from the ventral surface. The visceral sac is 

 cleft longitudinally, and the left half of the mantle has been thrown 

 back to exhibit the branchia and the aperture of the male organs at 

 the moment of expulsion of the spermatophore. a, funnel; 6, vesicle 

 containing the Hectocotylus ; c, eye ; d, aquiferous aperture ; e, man- 

 tle ; /, branchia; g^ branchial heart; h, flask; i, spermatophore 

 passing out. 



Fig. 2. The same. The mantle is cleft and thrown back, the funnel is taken 

 away ; the fibrous envelope of the abdominal cavity is cut so as to 



