IX 



PHYLUM ECHINODERMATA 



403 



The ccelome contains a fluid in which float numerous amcebo- 

 cytes, simitar to those of the Starfish, and also a uuinber of 



gen op 



- raxji oss 

 inter oss 



- qen gIm. 

 maa can 

 ini ves 



^gen.gl 



rcsft 

 — circmtcs 



long.7KU8 



b.w 



Firs. 329. — Internal organs of a Holothurian as scon when the body-wall is divided along 

 the middle of the dorsal surface, b. w. body-wall ; circ. mus. circular layer of muscle 

 cl. cloaca ; el. op. cloacal opening ; Cur. org. Cuvieran organs ; gen. ap. genital aperture 

 gen. du. genital duct ; gen. gl. gonad ; int. intestine ; inter. oss. inter-ambulacral ossi 

 cles ; int. vet. intestinal haemal strands ; long. mus. longitudinal band of muscle ; unci. can. 

 madreporic canals ; mes. mesentery ; pol. ves. Polian vesicles ; rod. amb. radial ambulacral 

 vessel ; rod. ost. ambulacral ossicles ; ri. bl. ves. ring strand of haemal system ; resp. respira- 

 tory trees ; ring-ves. ring-vessel of the ambulacral system ; stom. stomach. (After Leuckart.) 



flattened nucleated corpuscles containing a red colouring matter 

 — haemoglobin — almost identical with that which gives the red 

 colour to the blood of the higher animals. 



D D 2 



