260 Prof. M'Tnlosli's Notes from the 



deeply stained. The lateral sinuses leave only a small portion 

 of the gut bare above the ventral vessel in front of the fore- 

 going sections, and the ova occupy the lateral regions^ though 

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

 body enlarges, below the alimentary canal and the vessels. 



Tliefine sand-tubes 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 parti;il 

 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 the latter have not been met with 

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

 elementary condition, and in marked contrast, for i)i stance, 

 with that of such highly differentiated types as Bispira and 

 Branchiomma, where achordoid skeleton protects the central 

 ganglia and the neuroglia is much developed, the w^hole 

 central system being shielded by the tissues around it, and 

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

 various types by Eisig, and in the brain oi Lagis as shown 

 by Nilsson f. In Owenia and Myriochele the trunks from 

 the central system are not oesophageal, but run externally 

 in the hypoderm to join tlie ventral cord. Both Owenia and 

 Myriochele ap})ear to have certain larval characters, as seen 

 iu the young of various polychats, for instance, in Kleiuen- 

 berg's X Lopadorhynchus^ 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 Saccocirnis, as given by Gcjodrich §, also 

 presents certain analogous conditions. 



The alimentary canal of both Owenia nnd 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 Belg. t. xxxi. p. 159. 



t ' Beitrage der Keiint. des Nervensjstenis der Polycbseten,' Upsala, 

 ]912. 



X ' Die Enstechung des Aunel. aus der Larva von Lopadorhynchus,' 

 1886. 



§ Op. cit. 



