PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 289 



X zzz many ; -=- = few ; + = or more ; ^ =; irregular. 



Plan of insertion plates. 



Regular, brandling - 

 , do .- 



.do- 

 -do- 

 -do- 

 -do. 

 -do. 

 .do. 

 .do. 

 .do. 

 -do. 

 -do. 

 -do. 

 .do. 

 .do. 

 -do. 



{Lopltijroidea.) 



Regular, branching . . 



do ^.. 



do 



do - 



Unflssiired 



Regular 



{Acanthoidea.) 

 Regular, branching . 



-do. 

 -do. 

 .do. 

 .do. 



32 do. 



32a ! do 



33 V. all thrown forward. 



V. post, thrown forward. . . 

 do 



(Schizoidea.) 



) Regular, posterior valve i 

 i slit between 2 ridges. ( 

 Str. forward, deep slit 



(Placiphoruidea.) 



Str. forward, flat behind. . . 



Regular, flat behind 



Regular, ribbed behind 



do 



do 



do 



Slits in valve. 



(Mopaloidea.) 



\ Regular, posterior valve C 

 S laminated. \ 



Thrown forward, laminated [ 



do I 



Thrown foiward somewhat. | 



436 Thrown foiward much . 



44 Tail plate creuate behind. 



(Cryptoidea.) 



45 Regular, behind variable. 



4Grt Mopaloid 



456 do 



47 Coarsely mopaloid 



(Chitonclloidea.) 



48 ; Very sagittate 



48a .....'.do 



49 Intermediate 



8-10 



9 



7-8 



8 + ' 



Teeth. 



Eaves. 



1 

 1 



2+ 



1 



1 



1 



2+ 



1 



2 + 



1 



1 



1 



1 



1 



1 



1 



2+ 

 1 

 1 

 * 

 1 



GiUa. 



Sharp, normal ' Projecting (?) 



Shaip, hmg, sinootli. . ; Minute \ (?) 



Sh;iri>, normr.l Projecting Amb. 



do do Amb. 



do do Amb. 



do ... do Amb. 



do ... do Amb. 



do Projecting, long . Amb. 



do do Amb. 



do do Amb. 



Excui ved, plumate. . j do i Amb. 



Excurved, solid I Projecting I (?) 



Rough, propped . . . i Short | (?) 



Solid, not propped . . . j do (?) 



Solid, propped [ .... do (?) 



Sharp, curved i Short, spongy . . . Med. 



1 



1 

 1-2 



0-1 

 

 1 



Blunt, serrate j Short, spongy . 



. . . .do do 



Sharjjer, serrate do 



Sharper, serrate, long! Very short 



Blunt, fimbriate I Short 



(?) (0 



Blunt, grooved 



Longer, grooved. 



.--.do 



.-..do 



...do 



Long, smooth . . . 



Propped, smooth 



Short, sharp, smooth 

 Very long, sharp, 



smooth. 

 Kormal, sharp, 



smooth. 

 Very long, sharp, 



smooth. 



P r o j e ct in g, 



g r o o %■ e d . 



.. .do 



..-.do 



---.do 



Very short 



Moderate, not 



grooved, 

 iloderate, spongy: 



Projecting 



Short 



Moderate - . 

 Very short . 



Blunt, rugose Moderate. 



Sharp, serrate j Long 



Shai-p, long I Small 



Amb. 

 Amb. 

 Amb. 

 Amb. 



(0 

 (0 



(?) 



Amb. 



(?) 



Amb. 



(?) 

 (?) 



(?) 

 (?) 

 Amb. 



(?) 

 Amb. 



(?) 

 (?) 

 Med. 



None behind Deeply furrowed (?) 



Normal, serrate Moderate (?) 



Slightly propped .... Small Amb. 



Excurved do j (?) 



Sharp ! Minute j (?) 



Sharp, very long, do : (?) 



smooth. 



Long, propped Minute Med. 



Mod., simple Small (?) 



Very long, propped. . Minute, spongy. . Amb. 



' Small ' Med. 



Minute (?) 



Long, sharp, smooth 

 Very long, sharp, 



smooth. 

 Very long, sharp, ru- 

 I gose. 



i Crenate, sharp, 

 smooth. 



....do 

 ....do 



(?) 

 Long. 



Very long, smooth... Minute J. 



do ' do ' Med. 



do do I Amb. 



do None ! Amb. 



1 Viry short, except < 



i at sutures \ 



Mod. long in front. . . 



Distinct Post. 



. . . do Post. 



Minute (?) 



Pioc. I^at. Mus. 81- 



-19 



Feb, 33, 1883. 



