ON THE DIPLOCHOKDA. 353 



tlie buds tends to show that the subneural ghind is, from the 

 first, pre-oral in position, and does not move forward from the 

 coUar region, like the nolochord of Balanoglossus. 



Organs of the Endoderm. — There are a conspicuous pair 

 of grooves converging to the mouth (PL 24, fig. 12, o.g.), 

 which correspond with the oral grooves of Actinotrocha. 



The mouth {m.) leads into an area which I would consider a 

 stomodseum, giving off its subneural gland, and thence into a 

 pharynx [ph.). This is a spacious chamber which extends 

 some way down the body and finally opens through a short 

 oesophagus into the large stomach {st.), which, in its turn, 

 passes to the exterior by a broad intestine {int.). These parts 

 have all been described in more or less detail elsewhere, and 

 the pharynx alone need here detain us. 



Its walls are folded transversely into many sac-like out- 

 growths which present a somewhat regular arrangement, though 

 they may be largely due to shrinkage (fig. 13), but throughout 

 its whole length extends a pair of lateral vacuolated areas 

 which I would compare to the notochords ^ of Actinotrocha. 

 Though almost lateral in the extreme front end (PI. 25, 

 fig. 15, 9ich.) they come to occupy a dorso-lateral position at 

 the posterior end (fig. 17, 7ich.), the whole pharynx being 

 in this region, partially divided into ventral and dorsal halves 

 by lateral ridges. 



In tracing out the course of one of these notochords, we 

 first observe it in transverse section at the extreme front end of 

 the pharynx, covered by a mesodermic sheath formed mainly 

 by the collar coelom, and in this sheath originate strong 

 muscular bands which extend forward to be inserted in a 

 thickened mass of chondroid tissue lying between the epi- 

 stomial and collar coelomic walls. In the opposite face of this 

 chondroid skeleton are inserted the muscles which are con- 



' lu this case, and in Actinotrocha, the term uotochord is, strictly 

 speaking, a misnomer ; but, considering Batesou's name for Enleropneusta, 

 we can scarcely adopt the term "hemichord" (Mitsukuri). With those who 

 object to the term no to chord, applied to a lateral organ, the name " pleuro- 

 cbord " might find favour. 



