THE VOYAGE OF H.M.S. CHALLENGER. 



Challenger specimen owing to the deeper pigmentation of those parts. One of the 

 Copenhagen specimens has two tubercles over each eye, the other none ; and in both of 

 them the longitudinal markings seen on the ventral arms are wanting. 



Octopus cmstralis, Hoyle (PI. III. figs. 4, 5). 



1885. Octopus australis, Hoyle^ Diagnoses I., p. 224. 

 1885. „ „ Hoyle, Prelim. Eep. L, p. 98. ■ 



Habitat. — Port Jackson, Austraha; 6 to 15 fathoms, 

 immature. 



Two specimens, one ? , one 



Tlie Body is rounded, and wider behind than in front ; depressed, and with a well- 

 marked ventral median groove. A sharp narrow ridge extends along either side of the 

 body to the posterior extremity. The mantle-opening extends nearly half round the body. 

 The siphon is of medium size ; at first the lateral margins are parallel and then taper 

 rapidly to a blunt point ; it extends less than halfway to the umbrella margin. 



The Head is narrower than the body, and the eyes somewhat prominent, dorsally 

 rather than laterally. 



The Arms are unequal, the lateral being slightly the largest, and about three times 

 as long as the body ; they are slender and tapering. The umbrella is longer than the 

 length of the body ; larger ventrally than dorsally, and larger laterally than ventrally. 

 The suckers are prominent and closely set ; they are altogether larger on the lateral arms, 

 and extend in a double row to the centre ; the radial grooves are deep, and extend quite 

 to the margins. The specimens being females, no hectocotylus is present. 



The Surface of the back of the body, head, and dorsal aspects of the umbrella and 

 arms is covered with thick-set hemispherical pimples, which are also found on the inner 

 side of the membrane between the two dorsal arms, and on the inner surfaces of the arms 

 between the suckers. They are smaller and more sparse on the ventral surface of the 

 body. A large rough cirrus and a few pimples larger than the others are found over 

 each eye. A raised ridge passes backwards from the base of the siphon along the ventro- 

 lateral margin of the body, meeting its fellow of the opposite side at the posterior 

 extremity (PI. III. fig. 5). 



Hie Colour is deep purplish on the back, mottled on the sides, and cream below. 



Dimensions: 



Length, total. 



End of body to mantle-margin, 



End of body to eye. 



Breadth of body, . 



Breadth of head, . 



Eye to edge of umbrella (dorsally), 



Eye to edge of umbrella (laterally), 



Diameter of largest sucker, 



87 mm 

 20 

 22 

 19 

 14 

 16 

 23 

 2-5 



