102 K. MITSUKURI : STUDIES ON 



pair or so of openings (e). These minute buttons are not men- 

 tioned by Bell, but as they are placed much deeper than the 

 tables and ordinary buttons, they might easily be overlooked, and 

 were probably not noticed by Bell. 



The supporting rods of the pedicels and papillae are large 

 button-like plates and slender dendritic rods. Ventral pedicels 

 are supplied with large, and dorsal papillœ with small, end- 

 plates. 



Eeproductive organs are present on the left side only ; they 

 were still very small in the specimen examined. Polian vesicles 

 three, of which one was filiform and the other two more or less 

 club-shaped, the largest being 1.5 cm. long. Stone-canal single ; 

 dorsally situated on the right of the dorsal mesentery, with a pea- 

 shaped madreporic body. Cuvierian organ was a bundle of un- 

 branched finger-hke tubes attached to the stem of the respiratory 

 tree. Calcareous ring as shown in textfig. 20 a, the radial pieces 

 being 2 mm. high. 



The above species is close to H. oxurropa Slititee. But in 

 the latter species, the arrangement of ambulacral appendages in 

 regular rows can be detected neither on the dorsum nor on the 

 ventrum, the appendages are without white areas around the base, 

 and the dorsal papilloe lack calcareous deposits except small 

 end-plates ; while in my specimens of //. macleari they are covered 

 with numerous tables and buttons, the stone-canal is attached, 

 and Polian vesicles are 8 — 12 in number. 



This species also closely resembles H. infesta Sluitek in 

 having three kinds of calcareous bodies, but in that species, the 

 innermost layer consists of slender rods slightly thorny at the 

 ends. Further, the species show close resemblance to //. lamperti 

 Ludwig, H. curiosa Ludwig and H. fusco-luhra Theel. I should 



