210 A. E. Verrill — New Actinians. 



hexamerous, very numerous (up to 300 or more) in many rows, 

 long, tapered, inner ones far from margin, strongly entacmseous. 

 Mouth large, with two siphonoglyphs and many lateral folds. 

 Stomodaeum with two large basal lobes, making prolongations 

 of the siphonoglyphs; mesogloea of wall rather thick, very 

 flexible, strong ; ectoderm soft ; sphincter muscle very broad, 

 diffuse, mesodermal, moderately thick distally. Mesenteries 

 hexamerous, very unequal, numerous, with broad, thin, diffuse 

 longitudinal muscles ; 12 or more pairs perfect ; all the mesen- 

 teries fertile, except the directives and the rudimentary ones 

 of last cycle. 



The following species differs so much from the ordinary 

 species of Paractis, that it seems desirable to make it the type 

 of a generic group, especially as the true type of Paractis is 

 not yet determined. It is closely allied to Stomphia, but lacks 

 the thick collar and sphincter of that genus, and has a thicker 

 column-wall, lower down. The mesenteries are also more 

 graduated in size. 



Paractis (Archactis) perclix Ver. Figure 26. 



Urticina perdix Ver , this Journal, xxiii, p. 223, 1882; Bulletin Mus. Comp. 

 Zool., xi, p. 49, pi. vii, figs. 1, la, 1883; Annual Rep. IT. S. Fish Comm., xi, p. 

 534, pi. v, figs. 19, 19a, 196, 1885. 



This large and beautiful species has been pretty fully 

 described as to its exterior, in the works cited above. The 

 tentacles are about 384 in an average specimen. Alcoholic 

 specimen of medium size (diameter of column 1*5 to 2 inches) 

 when dissected had five complete hexamerous cycles of paired 

 mesenteries, and rudimentarv ones of the sixth cycle at the 

 periphery of the disk (formula, 6+6 + 12+24+48+96=192 

 pairs). Of these, 94, or all belonging to the first five cycles, 

 except the two pairs of directives, are fertile and bear large 

 gonads ; those of the first three cycles are mostly below the 

 stomodaeum, while those of the 4th and 5th are in the stomo- 

 deal region and extend nearly to the disk ; a few of the nar- 

 row rudimentary mesenteries of the 6th cycle also bear small 

 gonads, close to the disk. Near the lower part of the stomo- 

 dseum there are 12 pairs of perfect thin mesenteries, the six 

 lateral primaries being distinctly wider and stouter than the 

 rest. Higher up 12 more pairs (3d cycle) may join the sto- 

 modaeum and differ but little from those of the 2d cycle ; close 

 to the disk some of those of the 4th cycle may join the stomo- 

 daeum. Lower down those of the 3d and 4th cycles are free 

 and successively somewhat narrower, though still broad, while 

 those of the 5th cycle are much narrower, but all are regular 

 and fertile. The longitudinal muscles are feebly developed on 

 all the mesenteries ; even on the perfect ones they are scarcely 



