52 



OLD RED SANDSTONE EISHES. 



along the posterior margin of the shield of Eucephalaspis, and also along the posterior 

 margin of the joo^^mor or neck- plate of Auchenaspis, whilst there is no trace of such a 



Fig. 24. 



Diagram outline of the head-shield of Hemicyclaspis 

 Murchisoni. 



grooving along the posterior margin of the anterior piece of the shield in either Auchenaspis 

 or Didj/masjns. 



I was told by Dr. Anton Eritsch, of Prague, that he had obtained when in England 

 a specimen of this species showing parts of the body, but I have no details as to its 

 state of preservation, and am not certain that this was the species obtained. Fragments 

 of this species are not uncommon in the micaceous sandstone at Ledbury, which has 

 furnished a large species of Auchenaspis. There are only two specimens in collections, 

 which come from the finer argillaceous Tilestones, where it occurs with another 

 Cephalaspis and with the small Aucheiiaspis described by Sir P. Egerton as Au. Salteri. 

 As might be expected, the ornament is rarely preserved in the specimens from the ' Grits,' 

 whilst the two from the Ludlow Tilestones shoAv it admirably. 



7. Zenaspis Salweyi. PL XII, figs. 2, 5, 6 ; PI. VIII, figs. 2, 3, 4. 



Cephalaspis Salweyi, Egerton. Quart. Journ. Geol. Soc, vol. xiii, p. 283, pi. x, 1857. 



— ASTEROLEPis, /TarZey. Ibid., p. 503, 1859. 



— — Lankester. Brit. Assoc. Reports, 18G4. 



Name. — Named in honour of Mr. Humphrey Salvvey, of Ludlow. 

 Siratigraphical Position. — Cornstones, probably in a special horizon, with Scaphaspis 

 rectus and Pteraspis Crouchii. 



Characters (see the woodcut, fig. 26). — The large size of the tubercles, which are 



