172 Bulletin, Vanderbilt Marine Museum, Vol. IV 



Material examined : One specimen, dredged seventeen miles S. W. 

 of Pinta Island, Galapagos Islands, January 31, 1928, by the "Ara." 



Color : Although like all of its kind, this species is richly set with 

 chromatophores, which enable it to instantly change color, its most 

 accustomed color is a rich grape-purple, with a vivid violet-blue ring 

 above the jewel-like eyes. 



Technical description: This is a very large species, attaining a 

 total length of 3.5 feet, with the body about one and one-half feet long. 



The present specimen is 265 mm. long, from the tip of the longest 

 sessile arm to the posterior of the body. The body is 170 mm. long, 

 regularly cylindrical to the fin insertion, from this point abruptly 

 tapered to an acuminate tip; the fin is rhomboidal, wedge-shaped, 

 equal to two-fifths of the total body length; the insertion slightly 

 notched, the anterior margin slightly shorter than the postlateral 

 margin ; the lateral and posterior angles are nearly right angles. The 

 head is cylindrical, posteriorly necked, with two well-separated, promi- 

 nent lateral nuchal cartilages on each side. The orbit is large, of 

 characteristic shape. The ventral median excavation beneath the fun- 

 nel is deep. The funnel is large with an elliptical aperture. The 

 sessile arms decrease in length in the order 3, 2, 4, 1 ; the second pair 

 are furnished with a fleshy excrescence on the outer lateral margin; 

 on the third pair of arms this becomes a wider keel, while the fourth 

 pair have the upper lateral margin laminate. The suckers are in two 

 well-developed longitudinal rows with well-developed transverse 

 muscle ridges between each sucker and its neighbor. The horny ring 

 of an average large cup bears six to ten very acute, well-separated 

 teeth on the outer half, the shallower side of the ring may be smooth 

 or bear eight to ten small acute teeth. The tentacular arms are very 

 extensile, nearly as long as the body, the club not quite one-third of 

 the arm length, with a ventral keel on its distal half. The suckers 

 are in four approximate rows, small ones proximally, followed by 

 eight to ten much enlarged suckers in each of the two inner rows; 

 these larger suckers are two and one-half to three times the diameter 

 of those in the adjacent outer lateral rows. The suckers are set 

 obliquely in hollows created by the transverse muscle prominences 

 between the suckers. The horny ring of an average large sucker is 

 cut into 21 to 24 well-separated acute teeth, the teeth on the deeper 

 side of the cup being much longer and sometimes curved over apically. 

 The buccal membrane is produced into seven acute points. The beak 

 is very strong. 



