Miss Agnes Crane — Evolution ofihe BracMopoda, 113 



twenty-seven genera are recorded therein. They are grouped in 

 thirty-five families. Subfamilies are not recognized. This is about 

 one-fourth less than Mr. Schucliert's scheme required, but the actual 

 number of genera has been increased by forty-eight, viz. from 279 

 to 327, of which, strictly speaking, not one " persists unchanged " 

 from the Lower Cambrian to the recent period. 



We may be permitted to quote in conclusion the words of 

 Professors Hall and Clarke: '-To us the genus represents the 

 structural unit, a point of departure; species, diverse expressions 

 of the generic type ; families, associations of genera representing 

 the offspring of a common parentage." . ..." A classification is 

 a broken and punctuated expression of organic affinities and inter- 

 relations necessary to an easy treatment of any group of organisms, 

 capable of expressing many truths in regard to the development of 

 a race, but even in its most perfect state an index and a confession 

 of faulty knowledge." ' A. C. 



EXPLANATION OF PLATE V. 



Letters A. Atremata ; N. Neotremata ; P. Protremata ; T. Telotremata ; = Orders. 



p. paterina stage; o. obolelloid ; /. liuguloid; a. I. adolescent lingiiloid (Fig. 7). 

 S. Surviving genera. 



Fig, 1 a, b, c. A. Paterina Labradorica, var, Swantonensis, "Walcott, Lower 

 Cambrian, Vermont. 



Fig. 2. A. OboIeUa crassa, Hall (after Hall). 



Fig, 3. A. Oboh/s {Botsfordia) pulehra. x 3 (after Mathew), St. John 

 Group, N. B. 



Fig. 4. A. LinguleUa Daicsoni. Matliew. x 3, St. John Group, N. B. 



Fig. 5. A. Lingula lamellata, Hall (after Hall). Niagara Group, N. Y. 



Fig. 6. A.. Lingulops Jrhltfieldi, K-M. [ixiiex B.aW). x 3. Hudson River Group. 



Fig. 7. A. Lingula ricinil'ormis, Hall (after "Wiuchell and Schuchert). Lower 

 Silurian, Minuesota. p. proteguhim, or paterine stage; o. obolel- 

 loid ; a. I. adolescent liuguloid growth stage (greatly enlarged). 



Fig. 8 <r, i. A. Glottidia {Lingula) pgramidata, ^iim^sou (aiiex brooks). South 

 Carolina Seas. Obolelloid stages of shell gro^vth of the living 

 species. 



Fig. 9. T. Terebratidina septentrionalis^CovAhowy {iiiierl&ovs.e). Coast of Maine. 

 Showing liuguloid phase of shell o-rowth. 



Fig. 10, P. Ifiitorgina cuiqulata.'RiWmo^s (iitie-c'RAW). x 3. 



Fig. 11. P. Orthothetcs hns.^Wiiie [■AiXev'S.aW). x 3. 



Fig. 12. N. Discinolcpis gyanulata, Waagen (after Waagen). Cambrian, India. 



Fig. 13, N. ISchizambon {^()Jissus, Kutorga (after Hall). 



Fig. U. N. Trematis Ottawensis, Billings (after Hall). Nat. size. 



Fig. 15 a, b. N. ScMzobolus truncatus, "Hall sp. (after Hall), x 3. Genessee 

 Slate, N. T, 



Fig. 16 ff, b, c. N. Orbicuhidea minuta, Hall (after Beecher). Three growth 

 stages, showing the change from the paterina stage (a) with trans- 

 verse cardinal margin, "to the circular outline of the adult ; 

 a. paterina ; b. nealogic ; c. ephebolic stages. 



Fig. 17. N. Discina striata, Schximacher. West x\.fricau Coast. 



Fig. 18. N. 8chizncrania Jilosa, Hall (after Hall), Hudson Eiver Group. 



Fig. 19. N. Fholidops Cincinnatensis, Hall (after Hall), x 4. Hudson Eiver 

 Group. 



Fig. 20, N. Crania setifera, Hall (after Hall). Niagara Group. 



^ Handbook of the Brachiopoda, Part II. 1895. By James Hall and John 

 M. Clarke. 



DKCADE IT. — VOL. II. — NO. III. R 



