22^ TllK AMKRKWN .MONTHLY [Aup-., 



7 .— Kainil.N : DKll'IU I.IDA. Tw.) siu-Us. 



\. — MKnUl-I.AKY SlIKLI. SINOl.K. 



Two i>olar spines rtjual. Lithiitrnctus. 



Two polar spines un<M|ual. Druitpdlractitn. 



N«> pt»l:ir spini'S. Primornrinis. 



B. — MKHIIIAKV SHKM. nolULK. 



Two polar spines etjual. S/i/{alr(iclit--<. 



Two polar spines nneqnal. Xlitlntlrurtiut. 



8.— Family: SPONCIKI DA. Sponiry shell. 



A.^ — NO I.NNEU SHKI.I.. 



No inner latticed nu'dullary shell. SpoiufiijtrKnum. 



H. — INNKK I.ATTHKD MKDCLLAUY SIIEI.L. 



No polar spines. Spin\(jodnippn. 



Tw(^ ))olar spines. SpoivjalnictUH- 



('. MKUII.I.AKY SMKIJ, DolRI.K. 



.No jtolar spines. SponqoJiva. 



Two polar spines. SpoiH/oxijikax. 



15. — Two Clnuiiliirs. 



0.— Family: AKTISClDA. One shell. 

 No solid s)»ines or hollow tuhes on poles. Arliscus. 



1(1.— Family : CYPIIINIDA. Two shells, or more. 

 No p(»lar Inlies or spines. CypassiM. 



Two Jtolar tuhes. Cannartidinvi. 



C. — Many Chaiuhera^four ar more). 



11.— Family: I'ANAKTIDA. Four ehamhers. 

 No polar sj tines or tuhes. Pcmarlus. 



12. — Family: ZYCIAKTIDA. .Si.\ ehamhers, orinore. 

 No jiolar tultes. Onmatocnmpe. 



III.-DISCOIDAL SHELLS. 

 Here are 31 genera which are divided into two main sections 

 aeeordinjito the numher and character of the shells. 



A. — An outer le7iticular latticed shell, an intracap- 

 sular inednUary she//, simple or dauhle. 



13.— Family: PII ACODISCIDA. Mar^Mn wilhoutehamheretl 

 girdles. 



