some British Fossil Crustacea. 399 
largely faceted ; facial suture cutting the lateral cephalic mar-. 
gin in front of the angles ; eleven thoracic segments. 
Subgen. 1. Phacops (Em.). Pygidium with eight to twelve 
joints in the axis; hypostome simple. 
Subgen. 2. Odontochile* (H. & C.). Pygidium with twelve 
to twenty-two joints in axis; hypostome dentated. 
Subgen. ?3. Chasmops (M‘Coy). Eyes small, “ hiant ;” 
middle pair of lateral glabellar lobes obsolete. 
Subgen. 4. Portlockia (M‘Coy). Two anterior pair of lateral 
glabellar lobes obsolete ; lateral cephalic angles rounded. 
2. CaLyMENE (in a wider sense than Brongniart). Lateral ce- 
phalic angles not prolonged, exactly bisected by the facial 
suture ; eyes small, “ hzant;” glabella narrower in front than 
at base ; thirteen thoracic segments. 
Subgen. 1. Calymene (Br.). Axis of body strongly defined 
from the lateral lobes ; three segmental furrows to each 
side of glabella. 
Subgen. 2. Homalonotus (Konig). Axis not defined from 
lateral lobes ; no segmental furrows to glabella. 
3. TRimERocePHaLus (M‘Coy+). General character of Port- 
lockia, but without eyes or facial sutures. 
4, Asapsus (in a wider sense than Brong.). Cephalic and cau- 
dal shields nearly equal ; external cornea thick, smooth ; facial 
suture cuts the posterior margin within the angles; eight 
thoracic segments. 
Subgen. 1. Asaphus (as restricted to the type of A. corni- 
gerus, not British) = Hemicrypturus (Gr.). 
Subgen. 2. Isotelus (DeKay). 
Subgen. 3. Basilicus (Salt.). General character of [sotelus, 
but with many simple segmental furrows to pygidium. 
5. Inuanvs (Dal.). Head and tail nearly alike, axal furrows 
only indenting their margins; facial suture cutting the poste- 
rior margin ; pleurze with long, narrow, obscure facets and no 
pleural grooves. 
Subgen. 1. Llenus (Dal.). Ten thoracic segments, lateral 
cephalic angles rounded. 
Subgen. 2. Bumastus (Murch.). Resembling J//enus, but 
the thorax not trilobed. 
Subgen. 3. Dysplanus (Burm.). Like I//enus, but cephalic 
angles prolonged and only nine thoracic segments. 
6. Forsesta (M‘Coy). Glabella distinct ; facial suture cutting 
the middle of posterior margin ; pygidium with articulated axis 
* Dalmannia of Emmerich, not of Robineau-Desvoidy. 
+ For characters see below. 
