354 



AMMOCHARID^, 



peri-intestinal sinus, which in the neighbourhood of the oesophagus breaks up into a 

 plexus and gives branches to the ramified processes anteriorly, the current in which may 

 be constant in direction. The intestinal sinus in this form is placed between two thin 

 layers of circular muscular fibres, as in the Serpulids, and, as in them, bridles also 

 exist in the sinus, though they are fewer. He found the vessels in the branchia3 in 

 Owenia distributed in a homogeneous semi-fluid medium— from the coelomic space (and 

 the ova floated into them also), and the two hypodermic layers of which were connected 

 by bridles. He speaks of these as having also branchial cartilage. He could find 

 no trace of the cords in Owenia fusiformis in sections, and even in the fresh examples it is 

 difficult to see the nerve-cords. He, indeed, ultimately found them, but they had not 

 the normal histological characters. 



Gilson, again, thought that no coelomic epithelium lined the muscles internally, a view 

 opposed by Drasche and Ogneff. 



nx 



Fig. 135.— Transverse section of the anterior third of Owenia fusiformis, Delle Chiaje. gl. Mucous glands. 



sn. Vascular sinus round gut. 



Malmgren wisely separated, as Olaparede states, this group from the Maldanidse, with 

 which the elongation of their segments and their tube-dwelling habits correspond. 

 The inclusion of the intestine in a vessel is a feature at variance with all other groups of 

 the Polychasts except the Serpulids; and their cephalic branchiae are also peculiar. 

 Claparede thought the family intermediate between the Maldanidse and the Serpulids, a 

 group with which Sars, indeed, thought they should be united. 



The genus Ammochares was included in the Maldanidse in 1851 by Grrube, who, in 

 1846, described the species A. ottonis, but four years previously Delle Chiaje had given 

 an account of the same form under the name Oivenia fusiformis. 



This type was briefly alluded to by De Quatrefages (1865) at the end of the 

 Maldanidse, and adjoining Chjmenides and Arenia, the genus Ammochares being apparently 

 regarded as one of the Maldanidae. The only species mentioned is Ammochares ottonis. 

 The position of the group remained for a considerable time uncertain, some, like Grube 

 (1869), associating it with the Maldanidse. 



The Ammocharidse formed the sole family under LevinsenV (1883) Ammochari- 



1 Op. cit., p. 180. 



