82 



THE VOYAGE OF H.M.S. CHALLENGER. 



The Colour is a very pale piirplish grey, sliading off to a creamy white on the 

 ventral surface. 



The Jaivs are shown on PL I. figs. 4, 5. 



Dimensions} 



Length, total, . 



End of body to mantle-margin, . 



End of body to eye. 



Breadth of body, 



Breadth of head, 



Mouth to edge of umbrella between lateral arms 



Length of extremity of hectocotylised arm,^ 



Breadth of extremity of hectocotylised arm,' 



Diameter of largest sucker. 



Length of first arm, 

 Length of second arm. 

 Length of third arm. 

 Length of fourth arm, 





325 



mm. 





65 







70 







70 







50 







65 







8 







2 '5 







7 





Eight 



Left. 



170 mm.s 



200 mm 



215 „ 



215 „ 



225 „ 



220 „ 



. 220 „ 



220 „ 



The original Octopus hoscii was discovered on the western coast of Australia by 

 Peron and Lesueur, and received from the former the manuscript name Sepia rugosa, 

 Bosc ; Lesueur, however, was of opinion that it was not the same as the species figured 

 by Bosc,^ and therefore gave it the name of that naturalist, but without publishing 

 any diagnosis." 



Ferussac and d'Orbigny give a brief description,^ but do not say upon what it is 

 based, and in the British Museum collection there is a specimen named Octoptts hoscii 

 by Gray,'' though no trace can be found of what led him to this identification. Under 

 these circumstances it appeared better to accept Gray's opinion and to give a new 

 definition of the old species rather than erect the Challenger specimens into a new one ; 

 the more so as Gray's Octop>us does not disagree in any particular with d'Orbigny's 

 description. 



There is, however, a marked difference between it and the Challenger specimens in 

 colour (too great, I think, to be accounted for merely by the disposition of the 

 chromatophores), and the surface ornamentation is better marked in the latter, so I 

 have separated them as a distinct variety. 



It seems not impossible that Octopus tetricus, Gould, should be referred to this 

 species ; the description of the surface ornamentation is very similar, and it comes from 



1 Taken from the largest specimen ( $ ). 



3 Mutilated. 



'' Journ. Acad. Nat. Sci. Philad., vol. ii. p. 101. 



^ Taken from a smaller specimen, whose total length is 160 mm. 

 * Actes Soc. Hist. Nat. Paris, tab. v. figs. 1, 2. 

 " Geph. acet., p. 68. '' B. M. C, p. 12. 



