122 



IIIROSIII OIISHIMA. 



in a double row along each radius ; those of the three ventral radii 

 markedly well developed and more numerous than those of dorsal radius. 



Calcareous deposits of general perisome are either perforated plates 

 or primary crosses ; both rather delicate and beset near the centre with 2, 

 3 or 4 short pillars which often unite with one 

 another at apex, thus forming a kind of rudimen- 

 tary spire. The plates and crosses measure 

 o.i — o.2 mm. in diameter. The conical knobs so 

 characteristic of the plates of adult animals have 

 not yet appeared. Around the anus are found 

 five anal plates about 0.2 mm. in length, irregular 

 in perforation, and devoid of pillars. Pedicels have 

 oblong perforated plates or rods in addition to 

 end-plate. 



Mouth is open and leads into a narrow oesoph- 

 agus, which after a short run enlarges itself into 

 a stomach. The intestine shows the typical coil. 

 A pair of very short respiratory tree buds are 



given out near the end of intestine. 



Yolk granules 



can nowhere be found. 



Each of the five radial canals gives out only a 

 pair of tentacular canals, there being as yet no 

 budding out of secondary tentacular canals. In 

 this respect the young is of the Cucumarian type. 

 Stone-canal ends near the body-wall with a primi- 

 tive madreporic body. A single well developed 

 Polian vesicle present. Five retractors are dis- 

 tinctly separated from radial muscles. No primordium of gential organ 

 seems to be present. 



With regard to the mode of fertilization of ova and the way in which 

 the youngs escape from maternal body, I have no direct observation. 

 However it seems assumable that some of the gential tubes produce each 



A young taken out of the 

 body-cavity of a female 

 Pseudocucumis africanus, 

 seen from the left side. 

 Alcoholic specimen, X12. 

 One sees that the pedicels 

 are larger and more nu- 

 merous on the ventral side 

 than on the dorsal. Besides 

 are visible branched ten- 

 tacles, coiled intestine, 

 radial canals and scattered 

 calcareous deposits. 



