116 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



With the exception of one specimen from station 4416 all have six rays. Thirteen 

 six-rayed specimens have four madreporites symmetrically placed, the opposite 

 interradii involved in the fission being without them. Thus each of the two halves, 

 after splitting, has two madreporites. From 4416 there is a five-rayed specimen 

 with two madreporites, situated in neighboring interradii; and a six-rayed specimen 

 (R 7.5 mm.) on which I can find but one madreporite. 



The largest specimen, from station 4328, has R 15 mm. The crossed pedicel- 

 lariae are spaced between the spines and there is as yet no aggregation into circum- 

 spinal collars, nor do the spinelets exhibit any evident sheaths. The carina! plates 

 generally have four spinelets and most of the superomarginals three spinelets (the 

 first two or three have two) in the positions marked by the black dots in the figure. 

 (PI. 53, figs. 1, la.) The inferomarginals have two flattened, subtruncate spines 

 (occasionally three) which are much larger than any above them. The proximal are 

 sometimes slightly expanded and very shallowly gouge-shaped. There are five or 

 six dorsolateral spines on either side of the carinals in a fairly straight series extending 

 about a third the length of ray. 



The greater part of the surface of the superomarginals is marked by the minute 

 protuberances characteristic of a circumscribed area on the adult and the lateral face 

 of the inferomarginals has a small similar pebbled area (absent from the adult). 



The first pair of postoral plates is in p'artial contact as in Tarsaster. It is interest- 

 ing to note that when this animal divides in half, the cleavage splits equally two 

 opposite mouth angles. Consequently there are two small regenerating mouth angles 

 belonging to the three new rays; facing these are two normal mouth angles; and on 

 either side of these pairs an angle consisting of a normal mouth plate and a tiny 

 regenerating one. 



The straight pedicellariae, apparently confined to the mouth plates, are broadly 

 lanceolate with the tips of the jaws crossed. They are relatively broader than in the 

 adult. The crossed pedicellariae are figured for comparison with those of the adult 

 (pi. 52, fig. Zc-d). 



Type.— Cat. No. E. 1427, U.S.N.M. 



Type-locality.— Station 4554, northwest of Point Pinos, Monterey Bay, Calif., 

 60 to 80 fathoms, rocks and green mud. 



Distribution.— Half Moon Bay to south of San Diego, Calif., in 27 to 85 

 fathoms, fine sand and rocks; bottom temperature, 51 to 58.2 F. Records of station 

 4416, 448 fathoms, open to doubt as to correctness of label. 



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