364 Fossils of the Calciferous Sandoock. 



Locality and formation. — Mingan Islands, White Limestone. 

 Collectors. — Sir W. E. Logan, J. Richardson. 



Genus pileoceras, (Salter.) 



Mr. Salter has informed me that he intends to describe under 

 the above generic name some remarkable fossils that have been 

 found at Durness in Sutherlandshire Scotland, where they occur 

 associated with Ophileta compacta and others allied to species of 

 the Calciferous Sandrock and Chazy limestone. A species of the 

 same genus has been collected in this country, but lest any con- 

 fusion should take place I shall not describe it until I can see Mr* 

 Salter's paper. 



Genus lituites ? 



There are two species apparently of this genus in the Calcifer- 

 ous Sandrock, but the specimens are so imperfect that they cannot 

 be sufficiently characterised. 



CRUSTACEA. 



Genus bathyurus, (New genus.) 



Generic Characters. — Trilobites of a medium size, oblong oval ; 

 head thorax and pygidium sub-equal ; facial suture in front of the 

 eye nearly parallel with the longitudinal axis of the body, 

 reaching the anterior margin and behind the eye dividing the pos- 

 terior margin ; glabella sub-clavate conical or cylindro-conical 

 usually prominent and without lobes, but sometimes with several 

 obscure lateral transverse sulci, divided behind by a neck furrow ; 

 hypostoma oblong not forked, somewhat oval, an elevated margin 

 around the posterior two thirds in some of the species, muscular 

 impressions two, transverse or oblique, situated behind the middle ; 

 thorax in the species in which it has been observed with nine 

 segments ; pleurae grooved. 



The above genus is proposed to include serveral species of 

 Lower Silurian trilobites of which B. extans (Asaphus extans, 

 Hall), may be regarded as the type. It should perhaps be consid. 

 ered as a sub-genus of Asaphus of equal value with Megalaspis 

 (Angelin) from which it differs in the form of the head and pygi- 

 dium and in the number of the segments of the thorax. I shall 

 give some further illustrations of the genus hereafter. 



I have provisionally referred the following species to Bathyurus* 



