366 PROCEEDINGS OF THE NATIONAL MVSEl'M. vol. xxxvi. 



Disk naked; mouth central, very large; anal tube small, marginal. 



PP 25 35 45 ^'5 c, d abseut ; PP ^ and . long and slender, with a large 

 terminal comb ; pinnules from PP 5, , gradually increasing in length, 

 distally reaching approximately the length of the oral pinmdes; the 

 first three to six after PP 5, ,. bear globular genital glands at the base ; 

 side plates developed on the outer three-fourths of the pinnule am- 

 bulacra, best developed in the distal half. 



Genotype. — Comatilia iridometriformis. 



COMATILIA IRIDOMETRIFORMIS, new species. 



Centro-dorsal moderate, discoidal, the bare polar area flat, usually 

 with a more or less developed low rounded median tubercle, 1 mm. 

 to 1.5 mm. in diameter; cirrus sockets usually in a single, but often 

 in a more or less partially double or triple marginal row. 



Cirri XVI-XXVIII, 9-10, 5 mm. to 6 mm. long, exceedingly slen- 

 der and delicate; first joint short, about twice as broad as long; second 

 about tAvice as long as broad; third and fourth the longest, about 

 four times as long as broad; fifth slightly shorter; following joints 

 gradually decreasing in length, the antepenultimate being about half 

 again as long as its distal diameter; penultimate joint al)out as long- 

 as, or slightly longer than, broad ; second and following joints strongly 

 " dice-box shaped '' with expanded ends ; after the fourth the proximal 

 ends becoming less, the distal more expanded, so that the cirri as a 

 whole bear a close resemblance to those of certain of the Antedonidtie, 

 as Hathrometra and Iridometra; distal ends of the cirrus joints over- 

 lapping all around, but slightly more dorsally than ventrally, the 

 dorsal overlap, however, exhibiting no tendency to project anteriorly: 

 opposing sjiine terminal in position, directed obliquely forward, 

 arising from the entire distal half (or rather more) of the dorsal side 

 of the penultimate joint, about equal to one-half of the distal diameter 

 of the joint in length, usually forking transversely in its distal half, 

 more rarely breaking up into a number of small spines; terminal 

 claw approximately equal in length to the penultimate joint, mod- 

 erately stout, and evenly curved. 



Ends of the basal rays visible as rather prominent tubercles in 

 the interradial angles of the cal3'x ; radials very short in the median 

 line, but extending up in the angles of the calyx, separating the bases 

 of the IBr^ for a distance about equal to one-half of the basal diam- 

 eter of those joints, the condition in general resembling that found 

 in Calometra multicolor and in Bathymetra; two to four large oval 

 or round interprimibrachs are found in each interradial area, which, 

 however, are usually not quite contiguous ; IBr^ comparatively small, 

 oblong, very short, between three and four times as broad as long; 

 IBi\, (axillary) broadly pentagonal, about twice as broad as long, 

 the lateral edges about as long as those of the IBr^, making with them 

 an obtuse ang-le. 



