GaUij Marine Lahoratory, St. Andrews. 261 



vestibule by ciliary currents, it would in the first instance 

 be subjected to the action of the oesophagus, then passed in. 

 certain quantities into the stomach with its mobile glandular 

 walls, and subsequently sent through the funnel-like muscular 

 valve at the third septum into the intestine. The occurrence, 

 moreover, of the valve-like folds towards the posterior end 

 of the intestine in MyriocheJe , with the adjacent vascular 

 apparatus, would seem to indicate sj)ecial functions there, 

 both in regard to the contents of the gut and respiration. 



The central nervous system in Owenia and Mijriochele 

 does not conform to the typical three regions of the able 

 investigator Racovitza — viz., the paired " region palpaire " 

 giving branches to the palpi, the unpaired "sincipital" 

 giving branches to the eyes and tentacles, and the paired 

 " nuchal " to the ciliated sensory grooves ; or to those 

 of other authors of more recent date, the elementary con- 

 dition, perhaps, being associated with the feebly developed 

 and much modified prostomium, especially in Myriochele. 

 Fui'ther, the contrast between the typical form with its 

 circumoesophageal commissures is noteworthy, since the 

 homologues of these are as much hypodermal as the central 

 mass, for the nervous layer beneath the hypoderm of the 

 vestibule essentially differs. 



Another feature of moment is the absence of distinct 

 nephridia in both Owenia and Myriochele., the only repre- 

 sentative of a tube communicating with the coelom and the 

 exterior being Gilson's long hypodermic tube in the sixth 

 segment, and which apparently is indicated in Delle Chiaje's* 

 original figure as twozig-zag tubes bet ween two bristle-tufts; 

 and the author was also acquainted with the long mucous 

 glands and the general arrangement of the branchiae and 

 their blood-supply. The addition of two eyes to one of the 

 figures (2), with a pair of pinnate branchiae, is, however, 

 more or less imaginary. 



Again, the general structure of Owenia and Myriochele, as 

 representing thefamilyAmmocharid8e,gives small grounds for 

 their association under the same suborder, as Prof. Benham 

 in his earlier classifications f seemed to think, with the 

 Spionidge and Chsetopteridae in his group Spionoformia, 

 which really comprehends these only, since his Polvdoridse 

 and Magelonidffi, of which separate families are made, can 

 without undue laxity be placed under the Spionidae. Le- 

 vinsen, indeed, had previously made a separate group for 



• Discriz. e Nat. degli Anim. Invert, pi. 175. figs. 1-5 (1841). 

 t 'The Cambridge Natural History," vol. ii. p. '2h% (1896). 



