462 Rev. Canon Norman's Revision 



times at the apex and sometimes at the base of the arm, &c, 

 should not give rise to the same number of differences in the 

 mode of fecundation, and in the positions and manner in which 

 the seminal mass is placed upon the female, inasmuch as it 

 appears that the semen is hardly involuntarily or mechani- 

 cally emitted or poured out upon the eggs, but that this is 

 effected by conscious movements. What is furnished us in 

 this respect by simple reflection is also confirmed by observa- 

 tion. The seminal mass is actually attached to very different 

 parts and under very different conditions." Professor Steen- 

 strup, at the time he wrote that passage, was unacquainted 

 with any instances of hectocotylization among the Oigopsides, 

 and therefore thought that the discovery of hectocotylization 

 had given strength to d'Orbigny's divisions ; but, as has been 

 already pointed out, hectocotylization breaks down that classi- 

 fication. 



The following arrangement is suggested as one based pri- 

 marily upon the sexual distinctions. At the same time it will 

 not dismember d'Orbigny's natural group of Oigopsides, 

 which will, however, take a subordinate place, nor will it in 

 any way interfere with the arrangement by means of the shell, 

 but, indeed, proceed nearly pari passu with it. It breaks up 

 the Myopsides. 



Subclass DIBRANCHIATA. 

 Order I. OCTOPODA. 



MESARSENIA*. 



Hectocotylization takes place in the third arm of the male, 

 while some of the suckers of the other arms are in that sex 

 much larger than in the female in certain genera ; in others 

 the tips of the arms under modification. 



Order II. DECAPODA. 



A. Chondeophor a. 



Suborder I. OPISTHARSEN1A f. 



One of the first or dorsal arms generally hectocotylized. 

 Middle arms having some of the suckers in the male much 

 larger than in the female. 



* pco-os, middle, aparjv, male. 



f onto-dios, at the back, npa-^v, male. 



