510 



small, closely united plates, of unequal size and with no definite 

 arrangement. Each plate bears a spine about 1 mm in length which 

 terminates in a blunt point. There are similar spines borne all over 

 the upper part of the animal. The apines are not jointed to the ske- 

 leton but break off easily at the base, leaving small, nearly circular, 

 raised, white spots. The whole external appearance of the lower part 

 of the animal is thus quite similar to the body of the holothurians, 

 Sphaerothuria or Echmocucumis . But the spines when examined under 

 the microscope appear more like echinoid spines. 



The specimen had been cut in two vertically when it came into 

 my hands, but the internal anatomy thus revealed throws little light. 





(3^:=::- 







>^^;^^ 



if any, on the nature of the animal. In the upper chamber lies a 

 much-branched gland, resembling the gonad of a holothurian. Under 

 the microscope, this showed little structure, but I think there can be 

 no doubt that it is a reproductive organ. This gland is attached to 

 the floor of the chamber, while closely attached to the roof and sides 

 are several nearly spherical bodies, about 2 mm in diameter. These 

 are surrounded loosely by a thin membrane and seem to consist of 

 yolk. I can find no evidence whatever of any communication between 

 this chamber and the exterior and I do not see how there could have 

 been any during life. The lower chamber is almost wholly filled by 

 what appears to be part of a digestive tube, with a large lumen. It 



