40 EMBRYOLOGICAL MONOGRAPHS. 



31. Young Ilolothuria, aliovit in the stage of fig. 30 ; the vibratile cilia have ilisappeared, and the young Holothu- 



lian now creejjs by means of its tentacles and ambulaeral sucker. 



32. Young Ilolothmia, somewhat older, under compression, seen I'rora the dorsal side. The circular oral canal, 



the stone canal, the Polian vesicle, and the ventral ambulaeral eanal, are well seen. 



33-37. Auriculciria, v)ith dendritic and calcaremts gland. 



33-35, 37. From .lohannes Miiller, Ueber die Larven und die Metamorphose der Holothuiien uud Asterien (Pt. 3), 



1849-50, n. Y. Quoted above. 



36. From .Johannes JliUler, Ceber die Larven und die Metamorphose der Echinodernien, Yierte Abhandlung, 



1850-51, PI. I. Quoted above. 



33. 34. Two successive stages of the pupa, under compression. 



35. Holothurian larva of the same, with free tentacles, a, digestive cavity ; c, circular canal ; c', Polian vesicle ; 



f", the five branches of the circular oral canal leading to the tentacle ; e, calcareous oral ring ; /, tentacles ; 

 !7, stone caual, with its calcareous ring ; h, the lateral elastic spheres ; h', the odd terminal anal sphere ; 

 i, the terminal anal dendritic gland ; I; the remnants of the vibratile cord ; I, transverse bands of vibra- 

 tile cilia. 



36. Somewh.at more advanced young Holothuria, with a small ventral ambulaeral sucker : the vibratile cilia of the 



transverse bands have disappeared, d, the tentacular-like bodies at the base of the oral tentacles along the 

 calcareous ring ; /, circular canal ; /', Polian vesicle ; g, stone canal and its calcareous ring ; o, extremity 

 of the ventral ambulaeral canal. 



37. Young Holothuria, in a stage intermediate between figs. 35 and 36. 



