40S Mr. E. A. Smith on nn 



rare occurrence, judging from the few records of sucli abnor- 

 malities. C. Parona* has described and figured bifurcation 

 in an arm of " Eledone moschata,''^ an additional arm in 

 E. Aldrovandi, and a bifurcate arm in " Octopus vulgaris^ 

 These are the only records I have been able to discover of 

 such irregularities of growth. 



The present specimen presents a most remarkable instance 

 of arm-branching, the furcation not being confined to one 

 arm, but five out of the eight arras branch more than once. 

 Unfortunately the specimen, although sent home in formalin, 

 had evidently been dried previously, and all the viscera and 

 part of the head had been cut away, leaving only the body-sac, 

 the dorsal skin of the head, and the arms. 



The latter are connected at the base by a rather broad 

 membrane, broadest between the ventral pair and the lower 

 laterals, rather narrower between the two laterals, and quite 

 narrow between the upper laterals and the dorsal arms and 

 between the latter also. The membrane between the two 

 ventrals has been removed, so it is impossible to say anything 

 definite regarding its extent. I think, however, we may 

 regard it as fairly certain that it was as wide at this part as 

 anywhere. 



Arms. — The proportional length of the arms in such an 

 abnormal specimen is not of much importance. They are 

 rather equal in thickness, excepting the dorsal pair, whicii 

 are a trifle more slender than the rest. 



The r'ujlit dorsal is the only arm that does not exhibit 

 furcation. 



The left dorsal has two branchings, the first at about 

 6 inches from the mouth and the second an inch higher up on 

 the other side of the arm. This, again, trifurcates at the 

 end. 



The left upper lateral is normal for about 18 inches from 

 the oral centre, then bifurcates, the right branch again 

 bifurcating at a distance of 2 inches further up. 



The right upper lateral is regular for 13 inches and then 

 bifurcates, the branch being a mere stump half an inch in 

 length and looking as if the rest of it had been bitten off. 

 An inch and a half further up the arm a second furcation 

 occurs, and 2^ inches further the arm trifurcates, one of the 

 branches, like that lower down, being only a stump an inch 

 long and without any suckers. One of the longer branches 

 trifurcates at the tip. 



* Boll, Mua. Zool. Anat. Comp. Genova, 1900, uo. 96. 



