HARRIMANIA MACULOSA 1 23 



preserved fragmentary specimens of this species did not enable 

 him to make an exhaustive study of it. 



As to the epibranchial band, Spengel has also shown this to 

 have much the character in B, kti^fferi that it has in Harri- 

 mayiia} Unfortunately, however, he tells us nothing about its 

 histology. From the developmental side we have excellent 

 evidence from both Bateson (1885) and Morgan (1891), of the 

 presence of the esophageal notochord in ontogeny. Neither in- 

 vestigator has given a full history of the organ ; in fact their 

 references to it are rather meager. They are sufficient, never- 

 theless, to leave no doubt about its existence. Bateson, for ex- 

 ample, in summarizing the method of growth of the notochord, 

 states the matter in these words : The growth of the notochord 

 is due to : " i. A forward growth of the dorsal anterior portion 

 of the archenteron. This is supplemented by, 2, a longitudinal 

 constriction of the dorsal region of the pharynx, which gradu- 

 ally travels backward, separating a hollow hypoblastic tube 

 which remains open to the gut behind." Statement 2 is, of 

 course, the one that particularly concerns us here. His further 

 description and figures show that the skeletal crura are at the 

 ' longitudinal constrictions' of which bespeaks. How far back 

 these constrictions ' travel ' and what their relations are to the 

 gill clefts he does not make clear. Morgan's description of the 

 organ in the metamorphosing Toj'uarta studied by him is as 

 follows : " The digestive-tract oesophagus in this section shows 

 a tendency to division into two parts by lateral constrictions 

 in its walls, forming a larger lower part and a smaller upper — 

 the latter is directly contimiotis into the notochord farther for- 

 ward. In the corners of the folds are two thickened chitin-like 

 rods." (Page 424 ; italics are the author's.) His figures 58 and 

 59, PI. XXVni show it in characteristic form. In his theoret- 

 ical discussion (p. 445) the author remarks: "It is certainly 

 significant that the cavity of the notochord of Balanoglossiis is 

 continuous with the strongly marked dorsal groove of the oeso- 

 phagus." 



It would be of great interest to know more about the peculiar 

 thick plate with rolled-up edges found on the dorsal side of the 

 1 PI. XVI, figs. 53, 54, and 55- 



