82 G. F. MATTHEW; ILLUSTEATIONS OF 



Fig. 8. — Llnr/tthllu liiKjulonhs, ii. sp., ]. — 8, dorsal valve. — 8», ventral valve. — Sh, !,ame seeu iii profile. From 

 Div. 1.(7. See p. 34. 



Fi<;. 9. — Lhujuldla Dati:!tom,\\. sp., \. — 9, dorsal \'alve. — 9«, same seen in profile. — 9/', \eutral valve. — 9o, same seen 

 in profile. — 9(f, small ventral valve, showing nmsoular scar.s, etc. Frum I)i\-. I.e. See p. 33. 



Fig Iti. — Ihirtiiu Malthcui, AVakott. (A gasteropod.) Interior of tlie shell enlarged 12 diameters (after Walcott). 

 From Div. l.c (?). See p. 60. 



Fig. 11. — Linnarssonia Imnsnrga, Hartt, sp., '}. — 11, example of the dorsal valve partly exfoliated, exposing the 

 forked median furrows and the imprint of muscles near the hinge ; also, the characteristic rhombic" pro- 

 tuberances in front of the median ridge. — lln, same seen in profile. — lib, same seen from behind. — lie, 

 ventral valve partly exfoliated, shewing internal apical boss and foramen, and two small paired bosses 

 near the hinge line. — 11'/, same seen in profile.— lie, same seen from behind. From Biv. l.d. See 

 p. 35. 



Fic^ IL". — Linnarssonia misera, Bilhngs (?), 5. — 12, dorsal valve shortened by pressure, somewhat exfoliated, expos- 

 ing the thread-like median ridge, with its delicate branches, and behind these, two minute bosses close to 

 the hinge line. — 12<(, same seen in profile. — 12b, same seen from behind. — 12c, ventral valve, with faint 

 internal boss in front of the minute foramen ; also showing the false area at the hinge. — I2fl, same seen 

 in profile. — 12t', same seen from behind. From Div. l.d. See p. 35. 



Fig. 13. — Acrotreia Baihyi, n. sp., 1, — 13, dorsal valve partly foliated, exposing the median ridge with its branches, 

 the elongated median protuberance and the large paired bosses near the hinge line.— 13((, same seen in 

 profile. — ISb, ventral valve somewhat exfoliated, showing apical pit descending backward to the foramen, 

 aud the two small paired scars in front of the apical pit; also the hinge area, with median groove beliind 

 the foramen. — 13c, same seen in profile. From Div. l.d. (?). See p. 30. 



Fig. li.—Acrotreta (?) Gulielvd, n. sp., 4.-14, dorsal valve.— 14a, same seen in profile,— 146, interior of dorsal valve 

 of a young individual, enlarged r, exhibiting the central scar with three furrows before and three 

 behind, radiating toward the margin ; a'so two faint muscular (?) scars near the hinge line, and a faint 

 rhombic depression on the median line near the front of the valve.— 14c, ventral valve, exhibiting the 

 shallow, apical pit, with (large ?) foramen.— 14cZ, same seen in profile showing the revolute margins, cor- 

 responding to the involute margin of the dorsal valve.— 14f, cast of the interior of a ventral valve, 

 supposed to be of this species, exhibiting a large median lobe and flattened margins ; also a ring around 

 the foramen, and the paired muscular scars behind the apex of the shell. From Div. I.e. See p. 37. 



Fig. 15.— Acrolhek Mutthui, Hartt, sp., î, interior of dorsal valve, shewing the revolute posterior margins and nail- 

 like mesian ridge as described by Prof. Hartt ; also fine strire radiating from the umbo to the lateral 

 and anterior margins. — 15", same seen in profile. From Div. I.e. See p. 39. 



Fig. IG.—Acrotliele Matthnn, var. prima, r, ventral valve exhibiting the conical umbo close to the posterior margin.— 

 16o, same seen in profile. From Div. I.'/. See p. 41. 



Fig. m .—Acrothele MaUhwivar. lata, t, interior of ventral valve, with revolute lateral and anterior margins; two 

 pits in front of the foramen, and four minute ones close to the hinge line ; also diverging arched ridges, 

 in pairs, on each side of the foramen, and a low ridge on each side of the foramen extending back to the 

 hinge line.— ITn, cast of the same seen in profile, shewing position of the umbo in this variety. From 

 Div. l.b\ See p. 41. 



Fig. 18.— Kulorgina Lutonrcnsi^, n. sp., î, dorsal valve.— 18a, same seen from behind.— 186, ventral valve.— ISe, same 

 seen from behind. From Div. l.c": See p. 42. 



Fig. IQ.—Kutorgina {1) pterincoideK, n. sp., ',', (somewhat distorted if a brachiopod) shewing the peculiar hinge area. 

 From Div. l.c'. See p. 43. 



Fig. 20.— Orlhis Qimcocnats, '], dorsal valve.— 20a, same seen from behind.- 206, ventral valve.— 20r, same soon from 

 behind. From Div, l.c. See p. 43. 



