BRITISH NEMERTEANS, AND SOME NEW BRITISH ANNELIDS. 397 



end, at which the contraction ceases. A reversed movement by-and-by takes 

 place, the contents being propelled towards the snout. Anteriorly the two ves- 

 sels course forwards by the side of the oesophageal portion of the alimentary 

 canal without sub-division, pass along the sides of the proboscidian sheath in 

 special cavities (v), as in Litmus lactea, in front of the former, and reach the 

 ganglia, where they communicate. I have not actually seen a junction pos- 

 teriorly, but analogy would lead us to suppose such to exist. There appeared to 

 be little regularity or rhythm in the movement of the fluid in these vessels, both 

 of which were occasionally seen contracting from before backwards at the same 

 time. Generally, however, the contractions were alternate. 



In the fragmentary specimen from Balta, transverse section of the anterior 

 region (Plate X. fig. 2) showed 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) lay outside the latter. The cavity was partly filled in the prepa- 

 ration with minute granular cells. This agrees with the arrangement in Meckelia. 



Both Dr G. Johnston and Dr Williams mistook the ganglia for hearts, and 

 the inferior commissure for a connecting vascular trunk. The blood, says the 

 latter author, derived from the cutaneous system of capillaries, is poured by a 

 dorsal vessel into one of the chambers of the heart (the dorsal). From the 

 latter it is sent into the ventral cavity, and thence distributed over the integu- 

 mentary and intestinal systems. He, moreover, says the blood is red, and always 

 devoid of corpuscles. Such remarks are not based on correct observations. E. 

 Blanchard,* in his examination of Cerebratulus liguricus, describes the nervous 

 centres as lodged in a cavity into which the vascular trunks open, and this can 

 only refer to the post-ganglionic lacunae, though such do not by any means sur- 

 round the ganglia. I have not seen any vascular space surrounding the 

 "trompe" in front of the commissures, as described and figured by this author; 

 and the fluid of the proboscidian cavity could only have been seen there during 

 the ejection of the proboscis. He shows several longitudinal vessels in Nemertes, 

 which are not present in the British forms. I cannot agree with M. Van 

 Beneden'sj views of the circulation in Borlasia, for he describes the lateral ves- 

 sels as swelling out into vesicles when they approach the ganglia, and their con- 

 tents conducted to the exterior by a ciliated funnel. The erroneous nature of 

 this supposition has already been noticed under ' Cephalic sacs.' He also men- 

 tions that each lateral trunk posteriorly communicates only with that of the 

 opposite side, and concludes doubtfully thus : — " Le long des parois du tube 

 digestif, on voit en outre plusieurs vaisseaux, mais dont les aboutissants sont 

 difBciles a decourvir." Another deviation from accuracy is apparent from his 

 remark (under Cerebratulus cerstedii) that " En^ arriere un gros vaisseau tres- 



* Ann. dea Sc. Nat. 3 me aer. torn viii. pi. ix. fig. 5. f Op. eit. p. 12, &c. 



VOL. XXV. PART II. . 5 I 



