94 Prof. J. Steenstrup on Hectocotylus-formation 



with those which D'Orbigny has described after Tilesius in Sepiola 

 japonica, Til. About eleven acetabula are thus strongly elevated 

 on the outer side of the nglit and left arms, whilst the remain- 

 ing suckers are borne upon lower peduncles, which, however, 

 agree essentially with the others. As the so-called " covering 

 membrane" [Deckhaut) of the acetabula, which I have called the 

 lateral border of the arm in the preceding, is very strong and 

 broad on the outer side of the arm before these eleven suckers, 

 and the above-mentioned folds of skin are continued upon it, 

 some similarity is produced between this development and that 

 which we met with in Sepia, just as we have here the metamor- 

 phosis in the lower part of the arm, or principally in it. Lastly, 

 it must also be observed, that in all the five individuals both 

 arms are so obliquely twisted inwards, that it is evident a co- 

 operation between the outer side of both arms is facilitated 

 thereby. These two species are probably amongst the largest 

 in the genus, as they are of equal size with R. pnlpebrosa, Owen, 

 with which one must, in my opinion, be identical*, but there is 

 scarcely sufficient reason for supposing that the smaller species 

 would not exhibit peculiarities agreeing with these f. 



* The two species are easily distinguished fi-oin each other, as one has 

 extremely small suckers on the ckibs of the tentacles, as is the case, 

 according to Owen's description and figure, in Rossia palpebrosa $ , whilst 

 both males and females of the other species have very large suckers on 

 the clubs ; the middle row of these considerably exceeds the large spherical 

 suckers of the arms in size, by which pecidiarity this species also differs 

 notably from all other descrilifd species. To this remarkable form I 

 have given the name of Rossia Molleri, St]j., after our late coimtr^inan, 

 H. C. Moller, who has done such service to the MoUuscan fauna of Green- 

 land. The two dorsal arms, PI. III. fig. 1, are drawn from the male of 

 this R. Molleri. 



Induced by this and several other additions to the fauna of Greenland, 

 which will be referred to in this memoir, I seize the opportunity' of remind- 

 ing the reader, that both the original collection which served Moller as the 

 foundation for his " Index Molluscorum Grtenlandia;," and also his sub- 

 sequent collections for a more complete elaboration of this work, have 

 been presented to the Zoological Museum of the University by his father, 

 and that an enlarged and more complete edition of MoUer's Index, with 

 original figures, is being prepared by M. O. Morch, principally with the 

 aid of the above-mentioned material. 



t I make this remark with reference to a peculiarity- in the remarkable 

 Rossia dispnr, Riipp., noticed incidentally in Verauy's work on the Cepha- 

 lopoda of the Mediterranean. In this small species, which was first recog- 

 nized by its disproportionately large suckers on the uppermost lateral arms 

 (see Verany, I. c. tab. 23 d,f,g, h), for which Gray also has formed a sepa- 

 rate genus under the name of Heteroteuthis, according to a letter to the 

 author from Dr. Krohn, all the individuals furnished with these large 

 suckers have proved to be females ; whilst of another form, agreeing with 

 this in other respects, but destitute of the large acetabula, and for which 

 the name of Rossia affinis was thought of, only males have been met with. 



