626 Bkady and Norman — Monograph of the Marine and Freshwater Ostracoda 



2. Antennules without a terminal unguis. Mandible with or without 

 a small simple or bifid hirsute process near the base ; the palp 

 ending in ungues. First maxillse many-lobed, and furnished 

 with a subpediform 2-3 jointed palp. Second maxillae mi- 

 nutely-lobed, the last lobe generally fm-nished with distinct teeth ; 

 a small unjointed, sometimes tlu-ee-lobed, palp. Third postoral 

 appendages also maxilliform. No branchiae. 



A. Shell with a deep sinus in front for the protrusion of the 



antennae ; anterior extremity projected in rostrate or sub- 

 rostrate form. Mandible palp ending in ungues. Teeth of 

 second maxillae varying in form in different genera. Fam. 

 Cypridinidce, Baird, 1850. 



B. Shell oval, truncate behind, antennal sinus very shallow, a 



mere sinuation of the margin ; surface of valves rugose. 

 Antennules (?) without sensory organ. Antennae without 

 any secondary branch. Mandible — palp with last joint of 

 great size, ending in a distinct and large chela. Second 

 maxillae furnished with tooth. Fam. Rutidermatidce, Brady 

 and Norman. 



C. Shell oval or round, no antennal sinus. Last three joints of 



mandible — palp very short, without setae, each furnished with a 

 well-developed unguis. Second maxillae without teeth. Fam. 

 Sarsielltdce, Brady and Norman. 



Section III. — Cladocopa, Gr. 0. Sars, 1865. 



Antennae two-branched, both branches well developed, moveable and natatory. 

 Antennules also natatory, not geniculate, ending in long setae. Mandibles 

 distinctly toothed, with two-jointed palp, the first of which carries a small 

 branchial appendage. Only two pair of appendages posterior to the mandible, 

 the first bifid and natatory, the second membranaceous and branchial. No eyes. 

 Caudal laminae short, their posterior margin spinose and unguiferous. Fam. Poly- 

 copidoe, G. 0. Sars, 1865. 



Section IV. — Platycopa, G. 0. Sars, 1865. 



Antennae two-branched, flattened, resembling the feet of Copepoda ; basal 

 portion biarticulate and geniculate ; branches flattened, composed of few joints, 

 and bearing many setae on both margins. Antennules very large and strong, 



