114 Mr. J. C. Sumner on a new Nemo tine. 



XIX. — Description of a new Species of Nemertine. 

 By J. C. Sumner, Koyal College of Science. 



While looking over some Codium in search of Nudibranchs 

 at Fowey, in Cornwall, I found a small Nemertine, which 

 has proved, on subsequent examination, to be a species new 

 to science. 'Ihe specimen belongs to the genus Tetrastemma, 

 and is like T. dorsale in the shape and form of the body. 

 I propose to call it T. maculatum, on account of the con- 

 spicuous spots with which the animal is covered. Unlike 

 T. nigrum (also found on Codium) this animal is easily seen, 

 owing to its bright coloration showing up well against the 

 dark green background of the seaweed. For this reason it is 

 probable that it does not generally live on Codium, but with 

 other surroundings which would render it less conspicuous. 



Tetrastemma maculatum, sp. n. 



Diagnosis. Animal about 8 millim. long. Body cylin- 

 drical and tapering, resembles in shape T. dorsale rather 

 than the elongate forms, such as T.flavidum and T. vermiculum. 

 General ground-colour pure white ; dorsal surface beset by 

 large black spots, which become smaller and less numerous 

 on the sides, and almost disappear on the ventral surface. 



Remarks. These spots have a slight tendency to arrange 

 themselves in transverse bands, which for some reason or 

 other, for which I am unable to account, become much more 

 marked after death. The head is not very distinctly marked 

 off from the body by the cephalic groove, which is only to be 

 seen by careful scrutiny. The groove dorsally extends in a 

 posterior direction and ventrally anteriorly. Laterally well- 

 marked cilia are present. The eyes are situated very deep 

 in the head, and are almost easier to see from the ventral 

 surface than from the dorsal ; they are pale brown in colour, 

 and the posterior pair are wider apart than the anterior. 



I have been unable to make out much of the internal 

 anatomy, owing to the fact that the animal has not cleared 

 very well in oil of cloves. So far as 1 can see, however, 

 there is no material difference in this respect between this 

 species and its nearest allies. 



Undoubtedly T. maculatum is very closely allied to 

 T. nigrum, and, indeed, is only to be distinguished by the 

 great difference in colour. 



