TEREBRATULID®. 307 
Geological Distribution of the Families of Brachiopods. 
| “ 
5 
5 Neos a a 
=| | < 2 : ‘ > 5 h 
B/E Seles) /2e]8 
3 = ha 3 oO >] s a 5) 2 
Si/njASOla la |S)o |e | m 
A RTHROPOMATA. 
Terebratuhgweil'") xix lx) eile | «| &* iw | & 
ecid cick tts 672 th THUS) an | a | a 
Stringocephalidz, he 
Rhynchonellide,. . . . xl xl «el « il« | «| «il x |x 
Paiute et.) el SCE Wk iene te nat 
Spiriferidee, Pek ae eee hl ling oA beam 
Koninckinide, : hee: x i oben pe 
Strophomenide, SOE D8 TDS AE OU SOE 
Ptoductide, . . * | *& | ok | x 
LYOPOMATA. 
Craniade, Ee se oe oe eek. eset ee | oe 
Trimerellide, x 
Discinide, *)* | Kk] * | KI] & | & | x lk | ox 
Obolidee, . Tita, aaah, 
Lingulide, ee A en a, * 1x1] *e I] xe | x Kk | ok Ox * | x 
OrpER ARTHROPOMATA. 
(Apygia, Bronn. Articulata, Huxley.) 
Shell testaceous, articulated by hinge-teeth, with usually an 
internal skeleton-like testaceous process. Animal destitute of 
an anal aperture (Clistenterata, King). 
Famity TEREBRATULID. 
Shell minutely punctate; usually round or oval, smooth or 
striated ; ventral valve with a prominent beak, perforated near 
or at the apex, and attached by a peduncle passing through the 
perforation, or by a portion of the valve itself; hinge with two 
curved teeth; dorsal valve with a depressed umbo, a prominent 
cardinal process between the dental sockets, and a slender shelly 
loop. 
Animal attached by a pedicel, or by the ventral valve; oral 
arms united to each other by a membrane, variously folded ; 
sometimes spiral at their extremities. 
