NEMEETEA 



207 



C. tremaphoros C. B. Thompson. Body 12 cm. long, 3 mm. thick, 

 buff in color; head white, flattened, rounded in front: Woods Hole. 



ORDER 2. EETERONEMERTEA. (SCHIZONEMERTEA.) 



Body often very long; mouth behind brain; proboscis without 

 stylets; cerebral organ present; a caudal cirrus sometimes present; body 

 wall contains three muscle layers of which the outer is longitudinal and 

 between which and the circular muscles are the lateral nerves; cutis well 

 developed : 2 families and over 170 species. 



FAMILY LINEIDAE. 



Body usually very long, but in some species relatively short and 

 thick; a pair of conspicuous lateral sensory grooves usually on the head; 

 3 muscle layers in proboscis; the outer one being longitudinal; cephalic 

 gland small and slender: 10 genera and about 150 species. 



Key to the genera of Lineidae here described: 

 ! Caudal cirrus not present. 



6j Lateral sensory grooves wanting 1. PARAPOLIA 



6 2 Lateral sensory grooves present 2. LINEUS 



a, Caudal cirrus present. 



& t Lateral sensory grooves wanting 3. ZYGEUPOLIA 



b 2 Lateral sensory grooves present. 



c x Lateral body edges not thin ; animals cannot swim 4. MICBUEA 



c 2 Lateral body edges very thin ; animals swim 5. CEBEBEATULUS 



1. PARAPOLIA Coe. Body cylindrical anteriorly, flattened poste- 

 riorly ; head not set off from body ; without sensory grooves on the head ; 

 eyes not present; cerebral organs a pair of flat 



elevations: 1 species. 



P. aurantiaca Coe. Color orange; length 25 

 cm.; width 10 mm.; thickness 4 mm.: Vineyard 

 Sound, at low-water mark. 



2. LINEUS Sowerby. Body extremely long and 

 filiform or tape-like and very contractile; head 

 somewhat wider and tapering to a point; usually 

 with eyes : about 50 species ; cosmopolitan ; animals 

 cannot swim, and usually twist themselves into an 

 irregular mass. 



L. ruber (0. F. Miiller) (L. gesserensis 0. F. 

 Mill.; L. viridis Johnston) (Fig. 335). Body 

 cylindrical ; color very variable, being green, brown, 

 or reddish ; a single row of 4 to 8 eyes on each side 

 of head ; 20 cm. or more ; width 6 mm. : common under stones in shallow 

 water from Long Island to Greenland; Alaska; Europe; breeds in June 

 at Woods Hole. 



JB 



Linens ruber ( Verrill) . 

 A, whole worm ; B, 

 head, showing lateral 

 groove. 



