2 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



Family PELAGONEMERTID.E Moseley. 



Pelagic Nemerteans with a broad, flattened, leaf-like, gelatinous, very 

 hyaline body. Rhynchocoelome extending nearly the entire length of 

 the body. Proboscis unarmed. No cephalic grooves or organs of special 

 sense. Intestinal tract dendroccelous. 



Genus PELAGONEMERTES Moseley. 



Mouth and proboscis openings separate and distinct. Supraceso- 

 phageal ganglia larger than suboesophageal. Median dorsal vessel 

 lacking. Lateral diverticula of the intestine comparatively few in 

 number. 



Genus PLANKTONEMERTES, nov. 



A common external opening for the mouth and proboscis. Supra- 

 cesophageal ganglia smaller than suboesophageal. Median dorsal vessel 

 present. Lateral diverticula of the intestine very numerous. 



Planktonemertes agassizii sp. nov. 



Five specimens were taken as follows : — 



1. Station 3383, Lat. 7° 21' 0" N., Long. 79° 2' 0" W., 1832 fms. 

 6.51 A. M., March 8, 1891. Length 47 mm., greatest breadth 13.5 mm., 

 greatest thickness 3 mm., color "orange." Figure 1. 



2. Station 33G1, Lat. 6° 10' 0" N., Long. 83° 6' 0" W., 1471 fms. 

 7.33 A. M., February 25, 1891. Length of body 24 mm., length of 

 everted proboscis 28 mm., greatest breadth 9 mm., greatest thickness 

 2.5 mm., color "orange." Figure 2. 



3. Station 3388, Lat. 7° G' 0" N., Long. 79° 48' 0" W., 1168 fms. 

 G. 41 A. M., Marcli 9, 1891. Length 14 mm., greatest breadth 5.5 mm., 

 greatest thickness 1 mm., color "orange." 



4. Same station as No. 3. Length 38 mm., greatest breadth 16 mm., 

 greatest thickness 1 mm., color " orange." Figure 3. 



5. Station 3406, Lat. 0° 16' 0" N., Long. 90° 21' 30" W., 551 fms. 

 6.47 A. M., April 3, 1891. Length 37 mm., greatest breadth 16 mm., 

 greatest thickness 2 mm., color "pink." Figure 4. 



