'200 THE ATLANTIC. [chap. iv. 



and then, contracting a little, forms a rudely rectangular figure 

 round the bivium. The paired ambulacral grooves in the male 

 are shallow, not much deeper than the anterior ambulacrum 

 (Fig. 45) ; in the female the pore-plates of the paired ambulacra 



Fig. 44. — Hemiaster Philippii. The apical Fio. 45. — Hemiaster Philippii. The apical 

 portion of the test of the female seen from portion of the test of the male seen from 

 within. Slightly enlarged. within. Slightly enlarged. 



are greatly expanded and lengthened, and thinned out and de- 

 pressed so as to form four deep, thin-walled, oval cups sinking 

 into and encroaching upon the cavity of the test, and forming 

 very efficient protective marsupia (Fig. 4-1). The ovarial open- 

 ings are, of course, opposite the interradial areas ; but the spines 

 are so arranged that a kind of covered passage leads from the 

 opening into the marsupium ; and along this passage the eggs, 

 which are remarkably large, upward of a millimetre in diameter 

 when they leave the ovary, are passed, and are arranged very 

 regularly in rows on the floor of the pouch, each e^g being kept 

 in its place by two or three short spines which bend over it 

 (Fig. 46). 



Among the very many examples of this Hemiaster which we 

 dredged in Accessible Bay, and afterward in Cascade Harbor, 

 Kerguelen, there were young in all stages in the breeding- 

 pouches ; and although from the large size and the opacity of 



