No. 463] NORTH AMERICAN INVERTEBRATES. 429 
i. 
"er 
N 
Lad 
d 
yr 
Key. 
Without sucking disk ; intestine not convoluted. 
2. Proboscis o stylets; mouth posterior to brain; intestinal 
caecu 
3. Muscubi uei of body in two layers — outer circular and inner 
longitudinal — to which ‘a third — inner circular — is sometimes 
added; lateral nerves either eco muscular layers or imbedded 
in longitudinal muscles ; cutis absen Paleonemertea. 
31. Muscular walls of body in three main levers: of which the inner 
is longitudinal; lateral nerves outside circular muscular layer ; 
cutis well developed . .  Heteronemertea. 
2', Proboscis usually provided with idus 3h nont in front of brain, 
usually opening with proboscis in a single terminal or subterminal 
pore; intestinal caecum usually present; lateral nerves internal to 
muscular layers of body walls . Hoplonemertea. 
. With sucking disk at posterior end of bei i intestine convoluted 
Bdell 
ellonemertea. 
Order Paleonemertea. 
Paired intestinal diverticula emen ; a ; : : LO 
Paired intestinal diverticula presen 
Lateral nerves situated m diee Dr a ada of Mods 
s CARINELLA. 
Lateral nerves pue outside maci iavers in ER region, 
but imbedded in longitudinal muscles behind nephridial region ; intes- 
tine lobed, i without regularly paired diverticula ; cerebral sense 
organs wanting CARINOMELLA. 
Internal nr RE Re EEE in nephridial region ; 
mouth situated immediately behind brain; body not very slender ; 
head broader than neck ; nephridia well developed . CARINOMA. 
Internal circular muscles but little developed in any portion of body; 
mouth situated far behind brain; body filiform ; head sharply pointed 
CEPHALOTHRIX. 
CARINELLA. 
Body of somewhat homogeneous color, without definite markings . 2. 
With distinct longitudinal or transverse markings, or both 3. 
Body very soft, attaining a length of upwards of 2 meters TER fully 
extended ; deep red, orange, or bright vermilion 
C. rubra etn B, A. 
Body minute, very slender ; whitish and somewhat transluc 
C. pellucida ve 65 X. 
