•flfe Prof. J. Steenstrup on Hectocotylus-/orwfl^ion 



from that opposite to it, but also from all the other arms of the 

 animal, as it was, so to speak, inflated in a peculiar way through 

 its whole length, as shown in my fig. 9. On a closer examina- 

 tion, it appeared that the cause of this inflated state was, that 

 the otherwise spherical peduncles of the suckers had become 

 much elongated and cylindrical, and amalgamated together ; with 

 the obtuse apices of these cylinders, the suckers are united by 

 such thin and short filaments, that they almost appear as if they 

 were sessile ; their diameter is the same as that of their cylin- 

 ders, so that they nearly touch each other with their outer mar- 

 gins. This applies especially to the inner row of suckers, which 

 exceed those of the outer row in size, and project beyond them, 

 as is shown more distinctly by fig. 9", which represents this arm 

 seen from the ventral side, and fig. 9'", which exhibits two of the 

 suckers in both rows more strongly magnified. The first-men- 

 tioned figure also shows a remarkable dilatation of the skin 

 developed at the base of the inner surface of the arm, strongly 

 provided with muscles, and thus rendered capable of dilating 

 itself towards the sides and folding itself together, so that it 

 appears able to act as a prehensile apparatus or forceps. It is 

 here represented with the margins rolled together in the nozzle- 

 like form which it had in the spirit specimen. Below this 

 nozzle {Dille) there are seated four small suckers of the size and 

 form of those situated at the base of the other arms, from which 

 we see that this dilatation of the skin occupies the same position 

 on the arm as the dilatation on the arm of the Sepice -, and that 

 this apparatus has essentially the same import as the above- 

 described part in the genus Sepia, I cannot doubt. I have 

 already mentioned that fig. 5 on the first plate in Ferussac and 

 D'Orbigny best represents my male Sepiola as regards the geneml 

 habit and the strong spherical acetabula on the second and 

 fourth pairs of arms. 1 will now request that this figure may 

 be compared with mine in regard to the structure of the left 

 dorsal arm, and it will certainly be admitted that it is probable 

 that the peculiar form which this arm has received in the figure 

 must be founded upon such a structure as that which I have here 

 described. As all my females had small suckers where the male 

 possessed the large ones, and had the right and left dorsal arms 

 equally developed, so as to correspond with the other figures 

 which D'Orbigny has given of the species, I naturally regard 

 the often-mentioned fig. 5 as representing a male, and not an in- 

 dividual with a morbid or monstrous development, as D^Orbigny 

 explains this figure of his*. I also possess another male Sepiola 



* At p. 237 of his continuation of Ferussac's great work on the Cephalo- 

 poda (Ilistoire naturelie et particuliere ties MoUusques), D'Orbigny says 

 of Sej)iola atlautica ; — " Cette es[)ccc, dc mcuic que la Sepiola Rondclelii, 



