REPORT ON THE ECHINOIDEA——-MORTENSEN 9 
Agassiz), which occurs at about the same depths (3,890 to 4,950 
meters). 
Genus PARAPHORMOSOMA Mortensen 
PARAPHORMOSOMA ALTERNANS (de Meijere) 
Phormosoma aiternans DE MEIJERE, Siboga Echinoidea, p. 31, pl. 3, figs. 21-22; 
pl. 12, figs. 148-148, 1904. 
Paraphormosoma aliernans MorrENSEN, Monograph of the Echinoidea, vol. 2, p. 
152, pl. 4, figs. 5-8; pl. 76, figs. 14-16, 1935. 
FIGURB 1.—Part of peristome and adjoining interambulacrum of Hemiphormosoma pauci- 
spinum Mortensen, showing the gill slits, i. e., the two notches in the adoral edge of the 
primordial interambulacral plate. The two series of peristomial ambulacral plates 
belong to two neighboring ambulacra. xX 6. 
Locality.—Station 5585. 
Remarks.—It was a matter of great satisfaction to find in the 
Albatross material a specimen of this species, hitherto known only 
from the single specimen described in the Siboga Echinoidea. It is 
a good deal larger (74 mm. in diameter) than the type specimen (52 
mm. in diameter). Still, it is not adult, as evidenced by the fact that 
genital pores have not yet been formed. This indicates that the 
species must grow to a much larger size and is therefore among the 
larger forms in the Echinothuridae. 
