HISTORY OF RESEARCH. cxxxix 



b. Sub-family Tetragraptini (four main branches). 



(a) Dichograptus. — D. octobrachiatus and P. Logani. 



Temnograptus, sub-gen. — T. Milesi, T. reticulatus, T. onnulatus, T. 



diffusus, T. expansus, T. Richardsoni, and a new species, T. Barroisi 



(z=Rouv ill ig raptus Richardsoni, pars). 

 Glonograptus, sub-gen. — G. tenellus, G. flexilis, G. rigidus, G. multi- 



fasciatus, G. Thureaui. 



(b) Tetragraptus. — In the group of T. Bigsbyi,—T. Bigsbyi, T. bryonoides, 



T. denticulatus, T.fruticosus, and T. octonarius. In the group of 

 T. Headi, — T. Headi, T. alatus, T. quadribrachiatus. 



c. Sub-family Phyllograptini (four main branches which grow together dorsally). 



Phyllograptvs. — P.typus, P. ilicifulius, P. Anna, ]'. angustifolius, P. Luringi. 



Order II : Axonophora. 



3. Climacograptidi. — (Hydrotheca3 at right angles, outer edge straight, indented 

 by the thecal apertures.) This includes, in addition to Glimacograptus, the 

 Dicranograptidee, and the Grlossograptidse. 



(a) Retiograptus. — R. eucha/ris, R. tentaculatus, R. ? Geinitzianus. 



(b) Glimacograptus.- — The group of G. bicornis includes C. bicornis, the 



new species G. Nicholsoni, and G. antennarius. The group of 

 C. scalafis, G. Scharenbergi, G. typicus, G. estonus mut. Kvcher- 

 sianus, G. estonus, C.scalaris, G. caudatus, G. intemexus, G. Wilsoni 

 and (7. retioloides. 



(c) Dicranograptus. — D. ramosus, D. Glhn/aiii, I>. Nicholsoni. 

 Dicellograptus, sub-gen. — I), anceps, I), complanatus, D. divaricatus, 



D. Morrisi,!). moffatensis, D.intortus, P. Forchammeri, D. patulosus, 

 D. sextans, D. elegans. 



(d) Monoclimacis, n. g. — Rhabdosome with ouly one row of cells, hydro- 



thecas like Climacograptus. M. vomerinus. M. personata, M. en nu- 

 laris, M. continens, N. spinnlosa. 

 The genus Trigonograptus probably belongs to this group. 

 4. Diplograptidi. — (Rhabdosome with two rows of cells ; hydrothecae oblique; 

 outer edge toothed.) 



(a) Diplograptns. — 



Group I includes P. pristis, D. foliaceus, P. feretiusculus, P. sertularoides 



n.s., P. physophora, P. bellulus, P. gracilis, and P. palmeus. 

 Group II ( = Glossograptus) includes P. Whitfieldii, P. uplandicus and 



D. cf. acideatus. 

 Glyptograptus, sub-gen. — P. amplexicaulis, P. tamariscus. 

 Ortliograptus, sub-gen. — 0. quadrimucronatus. 



Petalograptus, sub-gen. — P. folium mut. ovato-elongata, P. folium, and 

 P. ovatus. 



