260 Piuf. M- In tosh's Notes from the 



deeply stained. The lateral sinuses leave onlj^ a small portion 

 of the gut bare al)ove the ventral vessel in front of the fore- 

 {joing sections, and the ova occupy the lateral regions, though 

 their position is variable, for they by-and-by appear, as the 

 body enlarges, belott' the alimentary canal and the vessels. 



Tiiefine san(l-tul)es of this form abound in such regions as 

 the Gulf of St. Lawrence, and occasionally one end (the 

 caudal) is terminated by a long tapering filament of the 

 secretion covered with sand. 



The main feature in forms like the present is the partial 

 differentiation of the nerve-tissue from the hypoderm with 

 which it is in continuity at its centre. No sheath is evident 

 anywhere, even in the more distinctly outlined nerve-cords 

 posteriorly. Yet the position of the cephalic centre and its 

 connection by two trunks with the ventral nerve-cord agree 

 with the general type. The innervation of the alimentary 

 canal seems to be carried out on a similar plan to that of the 

 main system, viz., by contact with a sensitive layer rather 

 than by special twigs, since thelattei" have not been met with 

 in sections. The whole nervous apparatus, indeed, is in an 

 elementary condition, and in marked contrast, for instance, 

 with that of such highly differentiated types as Bispira and 

 i?ra«c/yiow/»za, where a chordoid skeleton protects the central 

 ganglia and the neuroglia is much developed, the whole 

 central system being shielded by the tissues around it, and 

 so in the brain of Glycera as described by Gravier*, in 

 various ty[)es by Eisig, and in the ])rain o( Lapis as shown 

 by Kilssou f. In Owenia and Myriochele the trunks from 

 the central system are not oesophageal, bvit run externally 

 in the hvpoderm to join the ventral cord. Both Owenia and 

 Myriochele appear to have ceitain larval characters, as seen 

 in the young of various polychaets, for instance, in Kleiuen- 

 berg's X Lopadvrhynclius. in which, amongst other features, 

 the nervous system of the gullet may approach that of the 

 enigmatical pale layer in the vestibule of the present species. 

 The structure of Saccocirru.-i, as given by Goodrich §, also 

 presents certain analogous conditions. 



The alimentary canal of both Owenia and Myriochele 

 shows certain valvular complexities, doubtless associated 

 with the nature of their food — viz., mud or sandy mud con- 

 taining organic particles of various kinds. Carried into the 



♦ Bull. Sc. Frauce et Belo-. t. xxxi. p. 159. 



t ' Beitrage der Keunt. des Nervensystenis der Polvchaeten,' Upsnla, 

 ]912. 



t ' Die Enstechnng des Aiinel. aus der Larva von Lopadorhynchuf,' 

 1886. 



§ Op. cit. 



