386 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



broadly rounded. The extreme lateral portions of the dorsal surface are slightly 

 flattened or slightly and very broadly swollen. The sides of the IBr 2 and of the 

 first brachials and of the second brachials as far as the base of P! are flattened. Syn- 

 arthrial tubercles are very slight or absent. 



The 10 arms are about 110 mm. long. The first brachials are wedge-shaped, 

 nearly twice as long exteriorly as interiorly, with the ulterior sides united for from 

 two-thirds to nearly the whole of their length. The second brachials are slightly 

 larger and somewhat more obliquely wedge-shaped, more than twice as long exteriorly 

 as interiorly. The first syzygial pair (composed of brachials 3 + 4) is oblong, short, 

 rather more than three times as broad as long. The next six brachials are practically 

 oblong, about four times as broad as long. Those following are very obliquely wedge- 

 shaped, almost triangular, more than twice as broad as the longer side, soon becoming 

 less and less obliquely wedge-shaped and in the outer half of the arm very short and 

 oblong with the distal ends very slightly produced. 



Syzygies occur between brachials 3+4 and 9 + 10, again from between brachials 

 14+15 to between brachials 17+18, and distally at intervals of usually 8 muscular 

 articulations. 



P! is 9 mm, long, with 18 segments, slender and tapering evenly to the tip. The 

 first segment is about twice as broad as long, the second is nearly as long as broad, 

 the third is longer than broad, and those following increase in length so that the distal 

 are half again as long as broad and the last two or three are twice as long as broad. 

 The second-fourth or -fifth have a slight carinate ridge armed with numerous minute 

 spines on the side toward the arm tip. The sixth and following have the half of the 

 distal edge toward the arm tip slightly produced and everted, and dentate; on the 

 segments succeeding this dentate production of the distal edge soon involves all of 

 the distal edge, though always remaining most developed on the side toward the arm 

 tip. 



P 2 is 9.5 mm. long, with 18 segments, and is stouter than PI, with proportionately 

 very slightly shorter segments, though otherwise similar to it. P 3 is about as long 

 as P 2 or slightly shorter and is similar to it or very slightly stouter. It has 17 or 18 

 segments. P 4 is 6 mm. long, with 15 segments, resembling P 3 but very slightly more 

 slender basally and tapering more rapidly. 



The distal pinnules are slender, 6.5 mm. long, with 17 segments, most of which in 

 lateral view are from half again to twice as long as broad. 



The color in alcohol is purple, darkest on the ventral perisome and on the cirri. 



Notes. The specimen described above is one of those from Hood Lagoon, New 

 Guinea. The specimens from this locality are more or less intermediate between 

 typical papuensis and discoidea, though nearer the former. No examples of what 

 should be regarded as typical papuensis are at present available. 



In the small specimen in the British Museum labeled Tonga and Fiji the cirri 

 have 25 segments of which the outer are more spiny than usual. It resembles very 

 closely the specimens from Hood Lagoon and Port Moresby. 



Remarks. This form is simply an extreme development of Amphimetra tessellata 

 discoidea from which it differs in being of more slender and delicate build with more 

 slender cirri, which have longer and more prominent dorsal spines, and in having the 



