96 



RHEGMATODES TENUIS. 



into the interior cavity; the chymiferous tubes extending nearly to the 

 apex, leaving but a short digestive cavity, the edges of which scarcely 

 meet (Fig. 137), so that, when the actinostome is closed, the lips resem- 

 ble a piece of catgut tied by a string close to the end ; the marginal 

 j.._^ j3^ tentacles are long, gener- 



ally carried extended, and 

 when contracted twist only 

 two or three times, and are 

 not carried tightly curled, 

 as in Zygodactyla ; the ova- 

 ries are very narrow, and 

 extend almost the whole 

 length of the chymiferous 

 tubes, from the upper mar- 

 gin of the digestive cav- 

 ity, to about one tenth the 

 length of the radiating tube 

 from the circular tube ; the 

 ovaries hang down in two 

 masses on each side of the 

 chymiferous tubes ; there is 

 no connection between the 

 two pouches, except near 

 their point of attachment, 

 where they unite again. 



Younger specimens, meas- 

 uring about one and a half 

 to two inches, and not hav- 

 ing more than sixioen to twenty-four chymiferous tubes, reseml^le Sto- 

 mobrachium ; they differ, however, in the small number of tentacles. 

 The marginal capsules are large, elliptical ; the granules placed ftxr 

 apart, two in each (c, Fig. 138) ; the tentacles taper rapidly from the 

 base {t, Fig. 138), the walls are thin, the lasso cells scattered irregularly 



over the whole surface. At the base of the 

 large tentacles we find a very prominent pro- 

 jection (s. Fig. 138), in the shape of a small 

 tentacle opening into the circular tube; it is not 

 exactly a sjDur, as in Lafoea ; it develops only 

 after the rudimentary tentacles, being a button 

 scarcely to be recognized when the tentacle is 

 already quite well formed ; there are usually only rudimentary tenta- 



Fiff. 138. 



Fig. 137. Quarter of the disk of Fig. 136, seen from the actinal side. 



Fig. 138. A magnified portion of the circular canal, showing the position of the spur of the 

 tentacles, s, s, and of the marginal capsules, c, between the tentacles, t. 



