NEMERTEA 123 
In Langia the lateral cords approach each other dorsally : 
an arrangement which, according to Hubrecht, might result in 
the formation of a dorsal cord such as is found in the Chordata. 
The group as a whole is carnivorous, the larger species 
feeding on the tubicolous Chaetopods. They have the power 
of breaking up into pieces when irritated, and it is said the 
Schizonemertines can reproduce a head in connection with the 
various fragments. 
The NEMERTEA are classified as follows : 
(i.) Palaeonemertea.—WNo deep lateral slit on the side of the 
head. No stylet in the proboscis. Mouth behind the 
level of the cerebral ganglia. Carinella, Polia. 
(ii.) Schizonemertea.— A deep longitudinal slit on the 
side of the head, which leads to a ciliated duct which 
passes down to the cerebral ganglion, Lateral nerve 
trunks between the longitudinal and inner circular 
muscle layer. Haemoglobin in the nervous system. 
Mouth behind the level of cerebral ganglia. Lineus, 
Cerebratulus, Langia. 
(iii.) Hoplonemertea.—One or more stylets in the proboscis. 
Mouth generally in front of cerebral ganglia. Lateral 
nerves internal to the muscular layers. No deep longi- 
tudinal slits on the side of the head. Akrostoma, 
Drepanophorus, Tetrastemma, Geonemertes, Malacob- 
della. 
The older classifications divided the group into two sub- 
divisions : the Anopla and the Enopla. The former corresponded 
with the Palaeo- and Schizo-nemertines, the latter with the 
Hoplonemertines. 
