106 bulletin: museum of comparative zoology. 



Abdomen unsegmented, conically tapered, reduced in size, devoid of 

 appendages, and placed under the last thoracic segment, so that, in a 

 dorsal view, only the extremity appears below the seventh thoracic 

 segment. 



All seven pairs of legs present, and prehensile in character. 



Antennae rudimentary, composed of only a few articles and almost 

 inconspicuous, being placed on the ventral side of the head and invisible 

 in a dorsal view. 



Colypurus agassizi, sp. nov. 



Body gradaally increasing in width backward from the first to the 

 fourth free thoracic segment. The head is 2mm. wide, the first free 

 thoracic segment is 3 mm. in width, and the fourth free segment meas- 

 ures 4 mm. The length of the body is 5 mm. 



The head is produced in the middle anteriorly in a rounded lobe. 

 The sides of the head are also expanded in rounded lobes. P^our knob- 

 like bodies are situated in a transverse series on the dorsal surface of the 

 head, the two central ones being largest ; the lateral knobs are placed 

 one on each lateral lobe. The antennae are rudimentary, inconspicuous, 

 composed of only a few articles, and not visible in a dorsal view. The 

 tips of the mandibles project from the apex of the oral cone. 



The first segment of the thorax is coalesced with the head and bears 

 the first pair of legs. The following five segments are more or less sub- 

 equal in length, but increase gradually in width to the fourth free 

 segment. The last thoracic segment is longer than any of the preceding 

 segments and is posteriorly rounded. Each thoracic segment bears a 

 pair of prehensile legs, there being seven pairs altogether.^ 



The abdomen is inserted beneath the last thoracic segment, is conically 

 tapered, unsegmented, and devoid of appendages. 



Only one specimen was collected in the Eastern Pacific by the 

 Steamer "Albatross" in 1904-05 at station 4621. Lat. north 6° 36'; 

 Long, west 81° 44', off Mariato Point. 



The type is in the Museum of Comparative Zoology. 



1 In the specimen the third leg on the right side is broken off about the middle. 



