PLYMOUTH NEMERTEANS. 433 



Locality : Mewstone Ledge and Eame-Eddystone Grounds. Depth 

 10-30 fathoms. 



This yellow Nemertine reminds one very much of Frostoma candidum ; 

 it is very slender, however, attaining a length of nearly 2 cm., at a 

 breadth of less than 1 mm. This, the presence of a shining white 

 glandular area on the tip of the head in which the anterior pair of eyes 

 is situated, and of a similar very conspicuous glandular spot in the 

 anal region, characterize 'P. helvolum. 



Geographical distribution : Naples, 



12. Prostoma quatrefagesi, jBilrff. 

 Locality : One specimen from New Grounds. 



This species has no external markings. The colour is a bright 

 yellow and the animal was quite transparent. On account of these 

 characteristics it reminds one very much of F. candidum. However, 

 the proboscis sheath does not extend into the posterior third part of 

 the body. Moreover the number of the stylet sacs is quite unique 

 amongst English Frostoma's. Four pouches, containing at least twelve 

 accessory stylets, are present. 



Geographical distribution : Sicily and Naples. 



13. Prostoma herouardi, Oxner. (Bull. Inst. Oceanogr. Monaco, 

 1908, No. 127. PI. I, Fig. 1.) 



Locality : From hulks in Plymouth Sound, 



Once I got quite a number of these Nemertines from between 

 Laminaria roots. Their length did not exceed 5 mm. and they certainly 

 were not broader than f mm. The colour is a light flesh colour, with 

 a dark wine-red stripe on the dorsal surface, which extends from the 

 tip of the head to the end of the tail. Four eyes, arranged so as to form a 

 trapezium if the head is contracted, are situated in front of the brain. 

 Cephalic grooves are not present on the dorsal surface of the head. 

 The cerebral organs, however, are in front of the brain and are funnel- 

 shaped. The proboscis sheath continues to the end of the body; 

 proboscis with two stylet pouches, each containing two reserve stylets. 

 Central stylets as long as the handle, which is not narrowed in the 

 middle. The median dorsal red stripe is due to epithelial pigment. 



Geographical distribution : Eoscoff en Finistere. 



Genus Oerstedia. 

 Body cylindrical; head perfectly continuous with the body. Four 

 small eyes. 



1. Oerstedia dorsalis {Ahildg.). (Biirger. Monogr. PI. Ill, Figs. 

 30 and o(j.) 



