> < m r<>.\. 



c. Urabo of tail valve distinctly in front of the middle. 

 d. Ril>let> of lateral areas rather smooth and fine. 

 e. Dotted or spotted with Mm-. 

 /. Large, black, dote Bmall, 



ff. Small: dots large, 

 ee. Concentrically Hneated with brown or dark, cumhufi. 

 eee. Unicolored or blotched. 



/. 17 slits in head and tail valves together, perviridis. 



ff. 22-24 slits in head and tail valves together, quoyi. 



fff. 35 slits in head and tail valves together, subfuscus. 



ffff. 30 slits in head and tail valves together, bowenii. 



dd. Riblets of lateral areas granulose, irregular, or much 



forking. 



e. Lateral areas with 3-4 rows of pustules, granosus. 



ee. Lateral areas with forking or meshing riblets. 



/. Riblets 8-10, fine ; slits in head and tail valves 

 together about 40, i-iri/ulatus. 



ff. Riblets coar&er, netted ; slits fewer, stokesii. 



Umbo of tail valve about central. 

 d. Mucro depressed, slope behind it hardly concave, 



pellisserpentis. 



dd. Slope behind mucro very concave, burmmttin. 



bb. Central areas with a smooth band or triangular on ridge of 

 each valve. 

 Murro in front of the middle. 



i-entral areas curved or converging, 



e. Lateral areas sparsely pustulose-lirate, viridis. 



ee. Lateral areas with interrupted or netted lira-. 



tubereulattu, 



</</. Riblets of central areas parallel or diverging forward. 

 e. Lateral areas and end valves pustulose, granosus. 



ee. Lateral areas and end valves granose-ribbed, 



ofmaKeulatut. 



eee. Lateral areas 1 irate, nigrovircns, perviridis, densi I trains. 

 Muero about entral. 

 d. Lateral areas with low. smooth riblets, olh"irc us, (jereus, 



affin I*. 



dd. Lateral areas with feebly ^ranox- ril.l-t>, tusul'ir!*. 



ddd. Lateral areas with L r rano>- or noilo.-e ribs. 



. Lateral areas with o-l, pleura '2~> riblets, <Ki 



