PLATE 11-IV 



la,b — Beyrichia triberculata (Kloden) Boll., (a) Lateral view of female right valve 2.9 

 mm.; (b) Lateral view of male right valve 2.9 mm.; Silurian, Europe. (Kesling, Contr. 

 Mus. Paleontology, v. 8) 



2 — Howella ichinata Puri, lateral view, left valve, size 0.72 mm., Miocene, Florida. (Puri, 

 Jour. Paleontology, v. 30, no. 2) 



3 — Paracytheretta multicarinata Swain, lateral view of left valve, size 0.6 mm., Recent, 

 San Antonio bay, Texas. (Swain, Jour. Paleontology, v. 29, no. 4) 



4a, b — Procytheridea crassa Peterson, (a) left lateral view female carapace; (b) dorsal 

 view female carapace; size 0.66 mm., Jurassic, Wyoming. (Peterson, Jour. Paleontology, 

 v. 28, no. 2) 



5a, b — Howella echinata Puri, (a) exterior view of right valve; (b) interior view of left 

 valve; size 0.75 mm., Miocene, Florida. (Puri, Jour. Paleontology, v. 30, no. 2) 



6 — H eliomeroides teres Evitt, size 1.6 x 3.6 mm., lower Lincolnshire limestone, Middle 

 Ordovician, Virginia. (Evitt, Jour. Paleontology, v. 25, no. 5) 



7 — Sphaerexochus hapsidatus Whittington and Evitt, size 1.4 x 2.5 mm., lower Lincoln- 

 shire limestone, Middle Ordovician, Virginia. (Whittington and Evitt, Geol. Soc. 

 America, Mem. 59) 



8 — Palmotolepis sp., size 0.83 x 1.4 mm., Upper Devonian, New York. (Hibbard, Paleon- 

 tological Laboratories, Buffalo, N. Y.) 



9 — Bryantodus radiatus (Hinde), size 0.6 x 1.3 mm., Upper Devonian, New York. (Hibbard, 

 Paleontological Laboratories, Buffalo, N. Y.) 



10 — Polygnathus ordinatus Bryant, size 0.4 x 1.7 mm., Upper Devonian, New York. (Hib- 

 bard, Paleontological Laboratories, Buffalo, N. Y.) 



11 — Polygnathus linguiformsis Hinde, size 0.8 x 2.1 mm., Devonian, New York. (Hibbard, 

 Paleontological Laboratories, Buffalo, N. Y.) 



12 — Scolecodont (Oenonites ?), size 35 x 100 microns, Silurian, New York. 



13 — Astractura ordinati, diameter 220 microns, Miocene, Trinidad. 



14 — Lamprocyclas maritalis, size 148 x 254 microns, Recent, India. 



15 — Heliodiscus humboldti, diameter 280 microns, Miocene, Barbados. 



16 — Haliomma oculatum, diameter 148 microns, Miocene, Haiti. 



17 — Discoasterid, diameter 22 microns, Miocene, Sumatra. 



18 — Leiosphaera sp., diameter 48 microns, Devonian, Canada. 



19 — Hystrichosphaeridium sp., diameter 38 microns, Devonian, Canada. 



20 — Hystrichosphaeridium sp., body diameter 25 microns, length of spines 25 microns, 

 Upper Ordovician, Iowa. 



21 — Hystrichosphaeridium sp., body diameter 16 microns, spines 21 microns, Upper Or- 

 dovician, Iowa. 



22 — Cannosphaeropsis sp., body diameter 42 x 65 microns, overall size 80 x 90 microns, 

 Miocene, Virginia. 



23 — Angochitina sp., size 65 x 105 microns, Devonian, Canada. 



24 — Ampullachitina sp., size 85 x 115 microns, Middle Silurian, New York. 



25 — Nannoconus colomi (Lapparent) Kamptner, size 15 x 20 microns, Upper Jurassic — 

 Lower Cretaceous, Mediterranean region (Traite de Paleontologie, Tome Premier, 1952) 



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