84 SAN DIEGO SOCIETY OF NATURAL HISTORY 



REED (F. R. Cowper) — Continued 



Cheirurus bimucronota Murch. var. a C. cancrurus Salt., C. Keisleyensis n. sp., C. cf. 

 glaber Ang., C. cf. ilavifrons Dalm. ? C. (Pseudospliaerexochus) conformis Ang., C. 

 (P.) subquadratus n. sp. 



Sphaerocoryphe granulata Ang. Spliaerexochus mints Beyr., .V. latirugatiis n. sp. 

 Straurocephalus Mtircliisoni Barr. 



Acidaspis convexa n. sp. Liclias laxatus McCoy, L. affhiis Aug., L. conformis Ang. 

 var. Keisleyensis, L. Hihernicus Portl., L. hifiircata n. sp., L. hiilbiceps Phil. MS. 



Cvphaspis f Harkrssi n. sp., C\ (Toritqiiistia) n. subgeii. S'icliolsoni n. sp. 



PhiUipsinella parabola Barr. llarpes Jt'egelini Ang., //. cosiatus 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 Treraadoc 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. cla-viger Beyrich. Ordovician. 

 Glabella oval, often much inflated. Thorax 10 segments, grooved imperfectly. 



3. Cheirurus (Cyrtometopus) type, clavifrons Dalm. Ordovician-Silurian. 



4. Cheirurus (Hemisphaerocoryphe) type, pseiido-licmicranium, 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, S. cranium Kutorga. Ordovician. 



6. Cheirurus (Nieszkowskia) type, ccphaloccros, 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. articulatn Miinster. Devonian. 



This genus is almost entirely restricted to the Devonian. 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. 



Trinuclcus seticonns. 



Geol. Mag. London, Decade iv, vol. 4, 1897, pp. 427-428. 



