A NEW CAMBRIAN TRILOBITE. 141 



costate side lobes, introduces a feature quite at variance with the 

 usual appearance of the pygidium in Paradoxides, and more like that 

 in Conocoryphe ; if this species may be retained with M. torosus 

 in Metadoxides, there is greater reason for referring to this genus 

 the new species from Newfoundland. 



We have already called attention to the fact that the species 

 described by Meneghini under the name of Olenus Zoppii, and now 

 referred by Bornemann to his new genus Olenqpsis, bears a close 

 genetic relation to the genus Protolenus. In fact we may easily infer 

 from the development of the individuals in certain species of Paradox- 

 ides that 0. Zoppii is merely an advanced stage in the development 

 of a Protolenus, in which those advanced characters have become 

 fixed. Bornemann's representation of the development of 0. Zoppii 

 (in which, however, the figures appear to be somewhat conventional) 

 will readily bear out the relation of this genus to Paradoxides, and 

 justify our reference of Protolenus to the same rootstock. 



And this leads us to remark that one of the fossils collected in 

 Newfoundland last summer was a Micmacca, which by its somewhat 

 shortened eyelobe showed an advance in development beyond the 

 species found in the St. John Basin in New Brunswick. Another 

 trilobite, an Avalonia, from the Newfoundland Protolenus Beds has a 

 decidedly shortened eyelobe. It thus appears that one of the criteria 

 of the Protolenus Fauna as found in New Brunswick, i. e. that the 

 trilobites as far as known have continuous eyelobes, partially fails in 

 Newfoundland; and in so far as it does so, would indicate that the 

 Protolenus Fauna in Newfoundland (at least its middle and upper 

 part) is of a somewhat later date than in New Brunswick. So far 

 then, as opinion may be based on such data, the Protolenus Fauna in 

 New Brunswick is one of the oldest assemblage of trilobites hitherto 

 discovered, and that the migration of this colony has probably been 

 through Newfoundland to Southern Europe. If the Sardinian species 

 had come from the eastward we might reasonably have expected to 

 find with them Olenellus, Dorypyge, or some other genus that has been 

 elaborated in the region of the Pacific Ocean. 



Reference to Platelll — Metadoxides magnificus,T\.^. — Reduced |. 

 In tkis figure the different parts of the head-shield and the pygidium 

 are placed in position. The thorax is restored from loose pleura? 

 which in the restoration should be shorter and blunter ; number of 

 segments unknown. 



