22 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



Type locality.— ?>Mmon 823-38, 30-40 fms., San Juan Bay, Peru, 

 Februaiy 7, 1938. Two paratypes from Station 833-38, 10 fms., Inde- 

 pendencia Bay, Peru, Februaiy 10, 1938. 



Remarks. — In the smaller specimens of 2 mm. diameter the rosette 

 was regular and there were 4 rows of scales in each interradius. Only one 

 small scale separated the radial shields proximally. The marginal fence 

 contained only 7 papillae, and the upper arm plates were somewhat tri- 

 angular. The median oral papillae are spiniform and project above the 

 other papillae as in the type. The madreporite is swollen and considerably 

 larger than the oral shields in all specimens. This species can be distin- 

 guished from Ophiophragmiis chilensis Lyman and other members of the 

 genus by the large radial shields, rosette disk, median oral spiniform 

 papilla, and the unique enlarged and swollen madreporite. The name 

 stellatus has reference to the star formed by the large primary plates on 

 the disk. 



Genus AMPHIGHONDRIUS Nielsen 



Amphichondrius laevis, new species 

 Plate 4, Figs. 7-9 



Description. — Disk diameter, 3.5 mm.; arms, 16 mm. long. Disk pen- 

 tagonal and swollen, covered with large overlapping disk plates that form 

 a rosette. Surrounding the large central disk plate are 5 small triangular 

 plates, which with equally small distal triangular plates separate the 5 

 large radial plates from one another and from the central plate. There are 

 a few disk scales surrounding the large plates, while the remainder of the 

 disk is covered with moderate-sized, overlapping disk scales. Five or 6 

 rows of scales in each interradius. On the disk margin, midway between 

 the arms, is a large, conspicuous, elliptical plate, almost twice as wide as 

 long. The disk granulations of the interbrachial spaces below can be seen 

 distal to the marginal plates. Radial shields small, longer than broad, 

 length less than half the disk radius; separated within by one or two 

 disk scales, outer ends in contact. 



Upper arm plates triangular with broadly rounded angles, proximal 

 margin strongly convex. Basally the arm plates are broader than long; 

 distally they become longer than broad. The plates are separated from 

 one another by the side arm plates, which are finely granulated and meet 

 above and below. Spine ridge large and heavy, bearing 3 stout, erect, 

 subequal arm spines less than an arm segment in length, upper spine 

 stoutest and slightly longest. 



