374 BULLtrriN :g. united states national museum. 



spines, but from which it differs in the following details: spiracula in very definite 

 circumscribed areas, not confluent between the paxillar crowns; the regidar trans- 

 verse spiracular areas of interbrachial web of nohilis absent or only indicated irregu- 

 larly toward ends of rays; replacetl proximally by detached scattered small spiracu- 

 lar areas; furrow spinelet much shorter than segmental papilla; oral spines short 

 (one-half length of interradial suture, or less). 



Description. — Size large; general form stellato-pentagonal; R= about 100 mm., 

 r= about 70 mm., R= about 1.4 r. The second specimen has more evident rays 

 and deeper interbrachial arcs; R=82 mm., r = 45 to 52 mm.; R varies from 1.8 to 

 1.5 r. The interbrachial webs well shown in Sladen's figure of nohilis, and which 

 leave the paxillar area somewhat raised, anil sharply differentiated in both nohilis 

 and the present form, are very muscular and contractile, hence in preservation are 

 likely to differ widely in extent. //. Icahleri has deeper interbrachial arcs than 

 nohilis, but this may be due to preservation, as the two specimens differ so much. 

 Abactinal surface very similar to that of nohilis, the supradorsal membrane fairly 

 thick, and the less elevated interbrachial webs very fleshy. Paxillse with three 

 rather long, slender spines (occasionall}' four), which raise the membrane exactly as 

 described by Sladen for nohilis; moreover the spinelets are oriented the same way; 

 two usually aboral to the third, which is opposite to their interspace. There are six 

 rows of paxillae along each ray as in nohilis. Spiracula numerous and small, in very 

 definite irregular areas surrounded by a low fold of the integument, or the whole 

 area may be sunken; ten to one hundred spiracula to an area. On the lateral 

 fringe or web are scattered spiracula areas, some of which are elongated and are 

 homologous to the regular and more numerous parallel areas in /7. nohilis. These 

 elongated areas are more evident in the large specimens and occur beyond the middle 

 of the ray and are not so long as in nohilis. Proximally the areas of the web are 

 small and without order. From Sladen's description and figure of nohilis the spira- 

 cula of the paxillar region are not confined to sharply defined circumscribed areas, as 

 in I'oehleri, but are confluent among the paxillse. Osculum large, similar to that of 

 nohilis, the fan-like valves being a little higher and slight!}'' more acute; spines 

 twelve. The depression just back of the fans contains numerous spiracula, which 

 also occur in the web between the five fans; they also form linear areas between the 

 spines of the fans, but are variable in this respect. 



Adambulacral plates with an angular furrow margin bearing a single short 

 spinelet (2 to 2.5 mm.) invested in membrane, whicli is prolonged beyond the tip 

 (as in nohilis) one to three times the length of the spine. Aperture papillte rela- 

 tively somewhat larger than in nohilis, ovate, with a slight saccidus at tip (length, 

 3.5 mm., width 2 to 3 mm.). Tube feet large, in two rows; sucking disk small. 



Actinolateral membrane similar to that of nohilis, thick and flesh}-, traversed on 

 actinal surface by parallel grooves (between the actinolateral spines). In the type 

 these reach to the interradial line proximally but leave a smooth triangular area in 

 the interradius near the margin. The apex of this triangle is at the point where 

 the proximal actinolateral spines of neighboring rays meet in interradial lines. Near 

 margin the grooves are roughly parallel with border of disk, but, as just mentioned, 

 do not reach to the interradial line. Spines buried beneath the fleshy membrane, 

 the ninth the longest ; adorally from that point the tips of the spines nearly or quite 



