116 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



Anatomical notes. — More specimens of hrevispinus being available 

 than of the type form, it has been used for dissection. 



Stomach eversible, with a single chamber, a circle of small gland- 

 like out-pouchings of the dorsal surface representing perhaps the 

 rudiment of the dorsal stomach. Hepatic coeca rather short, reach- 

 ing about as far as seventh superomarginal plate; intestinal coeca 

 conspicuous, and shaped somewhat like a butterfly, the intestine 

 being where the body of the butterfly would be, and the 4 wings being 

 represented by symmetrical divisions of the coecum. Anal aperture 

 small. The greatest diameter of coecum equals about one-half r. A 

 strong muscle proceeds downAvard from the base of the hepatic coe- 

 cum and is attached to the first 3 ambulacral ossicles. Another pro- 

 ceeds from the fifth ambulacral ossicle and dividing into several 

 branches is attached to the wall of the stomach, below the coeca. 

 There are 10 of each of these. Gonads interradial, there being 

 a single tuft depending from the dorsal integument on either 

 side of the membranous interbrachial septum. Tube feet pointed, 

 but with a small button; ampullae strongly double; Polian vesicles 

 one in each interradius, except that of madreporic body, where there 

 are 2. They are of an unusual form, having a narrow proximal neck 

 and an enlarged distal kidney-shaped portion, around the edge of 

 which are many simple or divided fingerlike coeca. Superambu- 

 lacral plates well developed, absent from first 3 ambulacral plates. 



Between the superomarginal and inferomarginal plates a series 

 of tubelike diverticula of the coelom proceed horizontally toward the 

 outside. The position of each diverticulum is where the transverse 

 edges of 2 superomarginals and 2 inferomarginals meet, and the 

 largest pore is the interradial one, while the others decrease in size, 

 being quite small on the outer part of the ray. The outer end of the 

 pore has a corresponding position with reference to the 4 plates. It 

 ends blindly against the skin, but I have not been able to demonstrate 

 a papula, although from the inside the passages have the appear- 

 ance of papular pores. A natural supposition would be that they in- 

 dicate where papulae once existed. In Persephonaster oediplax the 

 pores are proximally still larger but no papulae can be discovered. 

 The same pores exist in Psilaster. 



Type.— C^t. No. 37002, U.S.N.M. 



Type-locality. — Station 5289. Verde Island Passage, north coast of 

 Mindoro (lat. 13° 41' 50" N.; long. 120° 58' 30" E.), 172 fathoms, 

 shells, sand. 



Distribution. — Balayan Bay, Luzon, and vicinity, and near Jolo 

 Island, 172 to 258 fathoms. Apparently this variety lives on harder 

 bottom than the type form. 



Specimens examined. — Six; 3 from type-locality and 1 from each 

 of the following stations : 



