504 



F. R. Cowper Reed — Blind TriloUtes. 



Eange. 



Carausia (Hicks) Cambrian. 



Dictyocephalites (Bergeron) ... ... ... Cambrian. 



Eryx {Knge]m) Cambrian. 



Aneucanthus (Angelin) ... ... ... Cambrian. 



Anopocare [AngeMvi) Cambrian. 



? ^vafowifl (Walcott) Cambrian. 



?£ at hi/not us (HaH) ... ... ... ... Cambrian. 



? Carmon (Beiir.) Ordovician. 



Solocephalina (Salter) ... ... ... Cambrian. 



? Telephus (Barr.) ... ... ... ... Ordovician. 



? Dindymene {Goxda) ... ... Ordovician. 



Areia {Ba-rr.) ... ... ... ... ... Ordovician. 



Flacoparia (Corda) ... ... ... ... Ordovician. 



Frosopiscus (Salter) ... ... ... ... ? 



Isocolus (Angelin) ... ... Ordovician. 



? Typhlonise-us (Salter)... ... ... ... Lower Devonian ? 



? Cyphoniscus (Salter) ... ... ... ... Ordovician. 



Conophrys (Callaway) f probably "I ... Ordovician. 



<SA)M««rfiJa (Billings) [ larval forms J ... Ordovician. 



Note. — Special visual organs (eye-spots) are developed in the 

 young of Trinucleus and in the Harpedidse, 



Geoitp 2. — Adaptive Foems. 



Eange. 

 Earpes henignensis, Barr. ... ... ... E'tage T>cl 1. 



Trinucleus Beds. 



E'tage Del 1. 



Lyckholm Beds, Keisley 



Limestone, Kildare L. 

 Keisley Limestone. 

 E'tage Del 1. 

 Trinucleus Beds. 

 E'tage Del 5. 

 Tentaculites Beds. 

 Tentaculites Beds. 

 Tentaculites Beds. 

 Upper Devonian. 



Ilhenus Angelini, Holm 



aratus, Barr. ... 



ccecus, Holm 



galeatiis, Reed . . . 



Keitzeri, Barr. . . . 



leptopleura, Linnars. 



Zeiellei'i, Barr. ... 



? Proetus dormitans, Kicbter 

 ? expcmsus, Richter 



Acidaspis myops, Eicbter 



Fheicops [Trimerocephalus) Icevis, Miinst. 



The genera Dindymene, Ti/phloniscus, and Carmon, which I have 

 with some hesitation placed in Group 1, may have to be regarded as 

 reversionary or degenerate types, on account of their primitive adult 

 cephalic features, combined with general morphological characters 

 which may be found to prove phylogenetic affinity with genera of 

 high rank. But we are not at present able to definitely decide this 

 point. The other genera in Group 1 which are marked with a query 

 (Salteria, Avalonta, Bathynotus, Telephus, and Cyphoniscus) may be 

 ultimately found to possess eyes. 



Barrande ^ gave in 1872 a summary of the blind genera and species 

 found in Bohemia, and incidentally noticed the foreign blind forms. 

 The classification, however, which he adopted took no account of the 

 phylogenetic principles which are now established, and therefore it 

 is to a large extent artificial ; but he recognized the fact that the 

 blind forms fall into two natural groups, characterized by the 

 presence or absence of facial sutures. On a comparison of the 

 classification and enumeration in his table as given below with that 

 which I have put forward, it will be perceived that a few additions 

 1 Barrande, Syst. Sil. Bob., vol. i, p. 131 ; ibid., Suppl., vol. i, pp. 155-162. 



