352 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vol. 50 



always more or less constricted centrally, the articulations expanded 

 (i. c, ''dice-box shaped"), at least in the proximal half of the cirri; 

 cirri smooth, or with more or less developed dorsal spines; terminal 

 claw (on penultimate segment) always prominent, at least on some 

 of the cirri; disk and ambulacra naked, rarely with small scattered 

 calcareous granules on the former ; costals united by bifascial articu- 

 1 lation, thin, broad, not very convex, often carinate, normally in appo- 

 sition laterally when the arms are closed, sometimes distinctly "wall- 

 sided" (by individual, not specific, variation) ; ten arms — abnormal 

 specimens of certain species occasionally have more, in which case 

 the distichals are 2 or 4 (3 -J- 4) — long and slender, evenly tapering, 

 the brachials triangular, almost always longer than wide (after the 

 third syzygial joint), becoming greatly elongated and often "dice- 

 box shaped" distelly ; brachials rounded, never carinate nor over- 

 lapping, but the distal edge is sometimes fringed with spines ; surface 

 of costals and lower brachials sometimes more or less covered with 

 closely set spines ; syzygia between brachials 3 and 4, 9 and 10, and 

 usually 14 and 15, the last somewhat variable, and distally at intervals 

 of 2 to 6 (usually 2 to 4) articulations ; the syzygia, as a rule, regu- 

 larly distributed in each species; pinnules with smooth segments, one 

 or more of the proximal pinnules always elongated and flagellate, 

 composed of elongated segments, but the first segment always short ; 

 distal pinnules with the first segment very short, the others greatly 

 elongated, more or less swollen at the joints. 



Color in life variable, purple, rose, red, orange, yellow 7 , green or 

 brown, usually more or less mottled or banded. 



Type of the genus. — Antcdon gorgonia de Freminville, 1811 = 

 Asterias bifida Pennant, 1777 = C 'omatula mediterranea Lamarck, 

 1816= Comatula Umbriata Miller, 1821, etc. 



The genus Antcdon, as here restricted, is practically equivalent to 

 the "Tenella group" of Dr. Carpenter. Two species, Antedon 

 pumila Bell and Antcdon parvicirra, obviously belong with the Ante- 

 don bifida type, and it is difficult to see why Dr. Carpenter placed 

 them, as he did, with Himcrometra milbcrti. The shape and propor- 

 tions of the brachials, cirri, and pinnules, and the regular disposition 

 of the syzygia at once proclaim their relationship with the small trop- 

 ical forms of the genus Antcdon, such as Antcdon nana, A. briseis, 

 and A. minuta. Antcdon is practically cosmopolitan, and occurs 

 from the littoral region down at least to 2,900 fathoms. The species 

 of this genus are peculiarly difficult of determination, as they are the 

 most brittle of all the Antedonidse, and it is very hard to secure them 

 in recognizable shape; thus it is that, although I have examined 



