70 THE VOYAGE OF H.M.S. CHALLENGER. 



while it is evenly continuous with the inner surface it does not rise up quite so high as 

 the outer, leaving the rough angles exposed. The two materials meet in a distinct line 

 near the bottom of the notch. 



This confirms what has been stated by previous observers, that the processes of repair 

 are differently carried out in the marginal and central parts of the shell. 



Family IV. Philonexid^, d'Orbigny. 

 Tremoctopus, Delle Chiaje. 



PMlonexis, d'Orbigny. 



Tremoctoims quoyanus (d'Orbigny), Steenstrup (PI. XIII. fig. 7). 



1835. Octopus (PMlonexis) Quoyanus, d'Orb., Am6r. merid., p. 17, pi. ii. figs. 6-8. 



18.38. PMlonexis Quoyanus, d'Orb., C^pb. acet., p. 96 ; Poulpes, pi. xvi. figs. 6-8, pi. xsiii. fig. 5. 



1861. Tremoctopus Quoyanus, Stp., Vid. Meddel. nat. Foren. Kj0benhavii, Aar 1860, p. 332. 



Habitat.— ~^onh Atlantic, April 28, 1876; lat. 17° 47' N., long. 28° 28' W. (at 

 noon) ; from the tow-net at night ; surface. Seventeen specimens (8 $ , 9 $). 



South Pacific, between the Sandwich Islands and Tahiti, September 15, 1875; 

 lat. 12° 8' S., long. 150° 13' W. One specimen, $ . 



South Atlantic (d'Orb.) ; Atlantic (Stp.). 



Of the seventeen specimens from the Atlantic above recorded, the three largest were 

 in a separate bottle labelled " in absolute alcohol," while a fourth was mounted in a cell 

 as a microscopic object, but, owing to the impossibility of identification in that condition, 

 it was transferred to a tube of alcohol. 



All the males had the hectocotylised arm (the third on the right side) stUl enclosed 

 in its sac, which had the form of a large tumour extending as far as the margin of the 

 mouth ; and in one case there were six suckers upon its inner surface close to the margin 

 of the mouth, belonging to the arm which was just issuing from its sac, an interesting 

 fact as showing that the sac oj^ens first at its oral margin (PI. XIII. fig. 7). 



The specimen from the Pacific Ocean was not very well preserved, the web between 

 the arms having been almost entirely destroyed, so that error in its identification is by 

 no means impossible. 



The largest female specimen obtained was so much larger than those measured by 

 d'Orbigny that it seems worth while to record its principal dimensions; it does not 

 appear to be sexually mature, and Professor Steenstrup informs me that he has never 

 seen any individual in that condition. 



