io'9) 
+ SAN DIEGO SOCIETY OF NATURAL HISTORY 
REED (F. R. Cowper)—Continued 
Cheirurus bimucronata Murch. var. a C. cancrurus Salt., C. Keisleyensis n. sp., C. cf. 
glaber Ang., C. cf. clavifrons Dalm. ? C. (Pseudosphaerexochus) conformis Ang., C. 
(P.) subquadratus n. sp. 
Sphaerocoryphe granulata Ang. Sphaerexochus mirus Beyr., S. latirugatus n. sp. 
Straurocephalus Murchisoni Barr. 
Acidaspis convexa n. sp. Lichas laxatus McCoy, L. affinis Ang., L. conformis Ang. 
var. Keisleyensis, L. Hibernicus Portl., L. bifurcata n. sp., L. bulbiceps Phil. MS. 
Cyphaspis ? Harkessi n. sp., C. (Tornquistia) n, subgen. Nicholsoni n. sp. 
Phillipsinella parabola Barr. Harpes Wegelini Ang., H. costatus Ang. 
Harpes species a-b. 
Woodwardian Museum Notes. On the evolution of the genus 
Cheirurus. 
Geol. Mag. London, Decade iv, vol. 3, 1896, pp. 117-123 and pp. 161-167. 
The author arranges the genus Cheirurus as follows: 
1. Cheirurus (Anacheirurus) type, C. Frederici Salt. Cambrian. 
The Tremadoc species has 11-12 thoracic segments, each of which is deeply 
grooved along its middle. Pygidium has 4 rings and 3 short pleural lobes on each side, 
which are grooved throughout and extend over the margin into spines. 
2. Cheirurus (Eccoptocheile) type, C. claviger Beyrich. Ordovician. 
Glabella oval, often much inflated. Thorax 10 segments, grooved imperfectly. 
3. Cheirurus (Cyrtometopus) type, clavifrons Dalm. Ordovician-Silurian. 
4. Cheirurus (Hemisphaerocoryphe) type, pseudo-hemicranium, Nieszk. Ordovi- 
cian. 
The basal lobes of the glabella are separated by a strong glabella, side furrow 
joining the neck furrow. ‘These lobes are less elevated than the rest of the glabella. 
5. Cheirurus (Sphaerocoryphe) type, 8. cranium Kutorga. Ordovician. 
6. Cheirurus (Nieszkowskia) type, cepialoceros, Nieszk. Cambrian and Ordovician. 
7. Cheirurus (Pseudosphaerexochus) type hemicranium Kutorga. Ordovician. 
The characteristics of the above two genera are 12 thoracic segments and the pres- 
ence of a longitudinal row of puncta instead of a furrow on the inner portion of each 
pleura. 
8. Cheirurus (Group 1 with cyrtometopian pygidium) type, C. Exsul Beyr. Or- 
dovician-Silurian. 
In this group the anterior pleura of the tail are enlarged and project behind the 
posterior ones. 
Barton refers this group to Ceraurus. 
9. Cheirurus Group 2 type C. bimcronatus Murch. Ordovician-Silurian. 
In this group the pygidium has 3 pair of pleura with free ends. The fourth pair are 
represented by a single medium terminal piece. 
Barton refers this group to Cheirurus. 
10. Cheirurus (Crotalocephalus type, C. articulata Minster. Devonian. 
This genus is almost entirely restricted to the Deyonian. The important subgeneric 
characteristics are the continuous first and second side furrows of the glabella, the 
triangular basal lobes, which nearly or quite meet in the centre of the glabella at their 
apices, and the nearly straight obliquely directed third side furrows. 
Trinucleus seticornis. 
Geol. Mag. London, Decade iv, vol. 4, 1897, pp. 427-428. 
