126 COE 



i. Length 15 cm. or more ; very pale brown or whitish, with two 

 longitudinal dorsal stripes of deep brown ; proboscis provided 



with eight nerves N.gracilis, p. 142. 



II. Body moderately elongated ; proboscis sheath about one-half to 

 three-fourths the length of the body ; central stylet well devel- 

 oped , Paranemertes. 



I. Four or six pouches of accessory stylets ; proboscis with ten 

 large nerves. Translucent, pale orange anteriorly, flesh color, 

 grayish or very pale salmon posteriorly, color much obscured 

 by deep green of intestinal tract P. californica, p. 144. 



III. Body very small and slender ; two ocelli ; proboscis but little 



developed, central stylet minute ; no accessory stylets ; parasitic 



on crabs Carcinonemertes . 



i. Only 4-6 mm. long when sexually mature; color orange or 

 reddish ; parasitic on the egg masses of Epialtus and per- 

 haps other crabs C. epialti, p. 151. 



IV. Body rather short and thick ; proboscis sheath reaches nearly or 



quite to posterior end of body ; proboscis large, central stylet 

 well developed. 



aa. Ocelli do not extend posteriorly beyond the brain ; basis of cen- 

 tral stylet usually rounded posteriorly. 

 b. Body not very small. Ocelli usually numerous. 



Amphiporus . 



1. Rather slender, 10-25 mm. in length; yellow; very con- 



spicuous red blood vessels ; five to ten ocelli in single 

 row on each side of head; basis very slender, about same 

 length as stylet A. cruentatus, p. 154. 



2. Slender, 50-90 mm. in length ; proboscis sheath about 



six-sevenths the length of body ; proboscis with fifteen 

 nerves ; basis of same length as stylet ; ocelli numerous. 



A. paulinus, ip. 155. 



bb. Body very small. Ocelli few ; usually four well developed 

 ocelli arranged in a rectangle Tetrastemma . 



1. Rather slender, 15-25 mm. in length, reddish-brown 



both above and below, except head, which is white 

 with sharply marked wreath of deep brown color on 

 dorsal surface. Blood corpuscles red. 



T. signifer, p. 156. 



2. Usually 20 to 70 mm. in length ; head provided with 



two pairs of very conspicuous, lateral, oblique fur- 

 rows. Color very variable, except head which is 



