148 K. MITSUKUEI : STUDIES ON 



ventrum are generally oval grains with a mixture of the rosettes 

 and biscnit- shaped grains, all of them being plumper than tliose 

 of the dorsum. In the ambulacral appendages, there are spicules 

 that are somewhat larger and irregular ; some are X-shaped or 

 even rod-shaped with two ends bifurcated, but none that may 

 properly be called supporting rods. 



Calcareous ring as in //. argus, etc. Polian vesicle one, 

 spherical, with not very long stalk. The stone-canal is attached 

 to the dorsal mesentery and runs forward, its somewhat large 

 madreporic body lying free in that window-like opening which in 

 this and allied species is found between the calcareous ring and 

 the mesentery. Cuvierian tubes abundant. They are found not 

 only on the two respiratory trees but also on branches arising 

 from the common part of these, which part is somewhat longer than 

 in other species. Of the said branches one is especially long. 

 The largest mass of the tubes was found on the left respiratory 

 tree. The genital bundle about 1 cm. behind the circular canal. 



A specimen of Flerasfer was discovered in the body cavity 

 during dissection, with the head in the cloacal cavity and the 

 tail pointed anteriorly. 



This sj^ecies is one of the group in which are placed //. 

 marmorata Jaegee, //. argus Jaeger, //. hivitlata, sp. n., etc. That 

 it bears closest resemblance to these, there can be no doubt, 

 though the coloration in life is so utterly different. The natives of 

 Oshima distinguish it by a different name "Shiro-Shikiri." Anatomi- 

 cally the species differs from the others mentioned in several details : 

 absence of large supporting rods in the pedicels, the free madre- 

 poric body of the attached stone-canal, spherical Polian vesicle, 

 and the arrangement of Cuvierian tubes. So that, I am strongly 

 inclined to maintain the distinctness of this species, although it 



