108 BULLETIN OF THE MUSEUM OF COMPARATIVE ZOOLOGY. 



PLATE XVI. 



Hyrnemopenccus dcbilis. Mandibular palpus of the left side of the female 



from Station 326, seen from beneath, enlarged eight diameters. 

 First maxilla of the left side of the same specimen, seen from beneath, 



enlarged eight diameters. 

 Tip of endopod of the same maxilla, enlarged twenty -four diameters. 

 Second maxilla of the left side of the same specimen, seen from beneath, 



enlarged eight diameters. 

 Tip of the endopod of the same maxilla, enlarged seventy-two diameters. 

 Sergcstcs arclicus Krciyer. Antennal scale of the right side of a male from 



off Martha's Vineyard, U. S. Fish Commission, Station 1030, enlarged 



four diameters. 

 Sergcstcs robustus, Lateral view of male from off Martha's Vineyard, U. S. 



Fish Commission, Station 893, enlarged two diameters. 

 Distal extremity of chela of the second leg of the left side of another male 



from the same station, enlarged twenty-four diameters. 

 Antennal scale of the right side of the same specimen, enlarged four 



diameters. 

 Appendage (petasma) of the protopod of the appendage of the right side of 



the first somite of the same specimen, seen from in front, enlarged eight 



diameters ; a, point of attachment to the protopod ; b, hooked stylet ; 



c, d, unarmed stylets ; c, /, g, terminal processes armed with invaginated 



hooks ; h, mesial line where the appendages of the two sides are hooked 



together. 

 Invaginated hook at the tip of process /, enlarged one hundred diameters. 

 Invaginated hook from the side of the same process, enlarged one hundred 



diameters. 



New Haven, Conn., June, 1882. 



