74 



HIROSHI OHSHIMA : 



three rows. The tentacles are supported by rods and X-shaped bodies 

 of various siz.es. The rods (j) arc usually recurved, 0.08 — 0.2 mm. 

 long, and are supplied at both ends with a few holes. At tip of the 

 branches of tentacles there are various forms of X-shaped bodies 

 (k — 1), which can be derived from the above mentioned rods. Their 

 length measures 0.06 — o. 1 mm. 



Calcareous ring. — Weakly calcified and imbedded in the connective 

 tissue, so that in young individuals it is liable to be overlooked. In 

 large individuals, however, they can be readily found and examined 

 Radial segment (a, RVR and RDR) 4.5 mm. long, 1.6 mm. broad, 

 and without posterior prolongations ; on its anterior margin are found 

 four notches, one for radial canal and the remaining three for 

 tentacular canals. Interradial segment (a, RDI) slender, of the form 

 of inverted Y, measuring 3 mm. in length and 1.5 mm. in breadth. 



Musculature. — The retractors are inserted to radial muscles at 

 different points of body length : the retractor of midventral radius is 

 inserted most anteriorly, while those belonging to dorsal radii arc 

 inserted most posteriorly. As measured in a specimen 51 mm. long, 

 the retractor of the midventral radius has its insertion at a point 24 

 mm. distant from the posterior body end, i. e., at about the middle 

 of the body; retractors of ventral lateral radii at a point 21 mm. 

 i. c\, about two-fifths the body-length, from same ; and those of dorsal 

 radii at 18 mm. i. c, about one-third the length, from same. In 

 contracted specimens both circular and radial muscles are quite thick. 



Polian vesicle.- — Usually single, situated in the left dorsal 

 interradius. Its length varies from 5 to 1 1 mm. Very often there is 

 found an accessory vesicle of 7 — 1 1 mm. length in the left ventral 

 interradius. 



Stone-canal. — Situated on the right side of dorsal mesentery, 

 ending with a kidney-shaped madreporite similar to that found in 

 Cucumaria calcigcra (STIMPSON) and first described by EDWARDS 

 [10, p. S7Ì- I' 1 length it reaches 2 — 2.5 mm., including the 



