8 NEMERTINES OF PLYMOUTH SOUND. 
the summer months had the white dots on the dorso-lateral regions 
of the middle and posterior parts of the body which mark the 
external openings of the generative organs. Whether the presence 
of these spots indicates sexual activity I do not know. Although 
many specimens were kept in captivity they did not spawn. 
Order 2,—MESONEMERTINI, Birger. 
The lateral nerves are pushed down into the body musculature. 
The body-wall consists of epidermis, a circular and a longitudinal 
muscular layer. Mouth behind brain. Proboscis without a stylet. 
Family CEPHALOTHRICIDA, MelIntosh. 
To this family, in addition to Cephalothrix, Biirger assigns Cart- 
noma. He characterises it as follows :—Lateral nerves situated in 
the longitudinal muscular layer. Neither cephalic grooves, clefts, 
nor side organs present. 
The negative characters here assigned, and which are repeated in 
the definition of the genus Cephalothrix, can scarcely be accepted in 
view of the recent positive statement by Joubin of the existence of 
side organs in Cephalothri« linearis, strengthening as it does the 
earlier assertion of Barrois (9) to the same effect. In 1877 Barrois 
stated, “Les organs latéraux du Cephalothrix linearis sont, en 
général, peu accusés ; c’est la, ce qui fait que plusieurs auteurs les 
ont laissé passer inapercus et ont dessiné le Némerte comme en 
étant dépourvu; je me suis assuré que c’était 14 une erreur: ces 
organes existent trés-bien chez le Cephalothrix adulte et y présent- 
ent, avec le systéme nerveux, une disposition analogue a celle des 
Lineus.’’ 
This statement has been persistently neglected, but now that 
these organs have been again described, and this time with figures, 
their existence can scarcely be doubtful. 
Genus CHPHALOTHRIX, Oersted. 
5. C. nrnearis, Rathke, Oersted. 
This species appears to be much less common than the next, and 
reaches a very much greater size. Though I have never found any 
specimens of the gigantic length of 50—60 cm., such as Joubin 
describes are obtained on the French coast, I have had several 
