114 ANATOMY OF THE ANOPLA. 



vessels, for the most part, lose their individuality, and, so far as I have observed, form an 

 elaborate vascular meshwork between the oesophagus and the inner muscular layer of the 

 body- wall (u, u, Plate XIX, fig. 1, and more clearly in Plate XX, fig. 2), again meeting 

 in the lacunas (s, s) in front of the cavity, and bathing the bulbs of the cephalic sacs 

 which lie therein. These lacunae or channels pass forward to unite at the ganglionic commis- 

 sures, and the granules of the contained fluid may be seen rushing forward in the one and 

 backward in the other. In addition to the smaller meshes surrounding the oesophageal region, 

 there are two larger spaces on each side of the proboscidian sheath in transverse section, which 

 may be held as the continuations of the dorsal vessel. The reticulations formed by this system 

 are noticed under favourable conditions in the living animal (e. g. as represented in Plate XIX, 

 fig. 1), as well as in numerous transverse sections. I have not been able to see any blood-vessel 

 in the tissues of the head in Lineus. A distended pale portion may often be observed in the 

 central line between the snout and the ganglionic commissures, as if the animal had gulped water 

 by the aperture for the proboscis, so as to distend the channel, but this has no connection with 

 the circulatory system. Transverse section demonstrates that there is no other channel in the 

 snout in front of the ganglia than that just referred to. 



In Borlasia Elizabeths a reddish coloration is frequently observed in the living animal on 

 the ventral surface at the white belts, showing that some contained fluid tints the dermal 

 tissues during its passage. On puncturing the dilated anterior end, for example in removing 

 the proboscis, a copious exudation of a reddish-brown fluid occurs. This presents many fusiform 

 or clavate corpuscles, probably from the proboscidian fluid ; but there are also present a vast 

 number of minute granules of a yellowish colour by transmitted light (reddish in mass), which 

 probably belong to the blood proper (Plate XVII, fig. 23). Many of the latter bodies show a 

 contraction in the middle, so as to resemble a figure of eight. 



In attenuate pale species, such as Lineus lacteus, Mont., MS., the intervention of an 

 elongated region between the posterior end of the ganglia and the anterior border of the 

 oesophageal region renders a special modification of the circulatory channels necessary. Accord- 

 ingly, it is found that after the fluid collects in the spaces in front of the alimentary organ, it is 

 conveyed by two long vessels forward to the ganglia, where the same ending occurs as in the 

 other species. These channels seem to be simple elongations of the ordinary lacunae, and are 

 represented in transverse section in Plate XXII, fig. 3 ; thus forming an intermediate link between 

 Lineus gesserensis and the still more extended post-ganglionic region in Cephalotlirix. 



In Carinella annulata two great longitudinal vascular trunks (Plate XXI, fig. 3, r) lie within 

 the inner or longitudinal muscular coat opposite the nerve-trunks, and they are peculiar on 

 account of their large size and the granular nature of their contained fluid. They form a coarse 

 network in the oesophageal region, as in Lineus, and are continued forward just within the border 

 of the snout to meet in a vascular arch. 



In the fragmentary specimen from Balta transverse section of the anterior region (Plate 

 XXII, fig. 2) shows a large ovoid and probably vascular tube (r) placed at the inner border of 

 the great longitudinal muscular coat on each side, while the nerve-trunk (n) lies outside the latter. 

 The cavity is partly filled in the preparation with minute granular cells. This agrees with the 

 arrangement in Carinella. 



Cephalothrix has also two great longitudinal vessels (Plate XXI, fig. 2, r) situated nearly 

 opposite the nerve-trunks (n), from which they are separated by the chief longitudinal muscular 



