MOLU'SCA. 35 



lessening in diameter towards the tips; about one hundred in 

 number on the longest arms, rather prominent, especially the largest, 

 alternating in two series, almost, if not quite, from the commence- 

 ment. Length from end of the body to angle between the upper 

 arms 20 milliin., width of body 13, length from subsiphonal open- 

 ing to the extremity only 10 ; largest arm, from mouth to tip, 40 

 millim. 



llab. Thursday Island, Torres Straits, 4-5 fathoms, sandy bottom 

 Q Alert'); Tort Essington (B. Mus.). 



This species (in spirit) is of a pale dirty olive tint on the ventral 

 surface and very much darker above. The inner surface of the 

 anus is also light olive, the suckers having a brown hue. At first 

 I was inclined to consider that this olive colour might be the result 

 of staining by the juices of an Aplysia which was contained in the 

 same bottle. On examining the type from Port Essington, which i 

 had not an opportunity of doing when drawing up the above 

 description, I find that the same colour prevails. 



2. Octopus tenebricus. (Plate IV. figs. B-B3.) 



Animal of a uniform dark purplish chocolate-colour. Body (in 

 spirit) longer than wide, smooth, bearing upon the back and sides 

 scattered cirri. Head as broad as the body, very prominent at the 

 eyes, much constricted in front and behind in the cervical region ; 

 also ornamented with a few tufts, the largest one being placed above 

 but slightly behind eacli eye. A small one in front of each eye and 

 a similar one just behind them appear to be constant in position ; 

 these are simple elongate papillae, whilst the larger ones are branched. 

 The web between the arms is rather small, externally papillose, and 

 extends in a narrow strip up the back of the arms, forming a sort of 

 acute carina. Upper or dorsal pair of arms smallest and shortest, 

 the two lateral pairs about equal and the ventral only a trifle 

 shorter, all gradually tapering to very fine points. Lower surfaces 

 narrower, bearing two rows of very prominent suckers, of which the 

 first four form a single series, the rest (about 120 on the longest 

 arms) alternating in position. The first cup is very small, the next 

 a trifle larger, and so on until about the tenth is reached, when they 

 attain their greatest diameter, namely lj millim. ; this size is 

 maintained a short distance up the arm, when the cups gradually 

 diminish as the extremity is approached. 



Dimensions. Body, from base of funnel to extremity, 13 millim., 

 width 11 ; longest arm 72 millim., shortest 50 in length. 



Hah. Port Uenison, ISLE. Australia, 3-4 fathoms, sand and rock 

 bottom. 



This species bears considerable resemblance to O. aculeatus of 

 d'Orbigny, but may be distinguished by the difference of colour, the 

 different relative length of the arms, the narrowness of their lower 

 surface, the greater prominence of the suckers, the regularity of the 

 uniserial four at the base, and the smaller number of the external 

 cirri or papillae. 



7)2 



