FOSSILS OF THE HUDSON RIVER GROUP. 451 



phns platyeephalus is principally found up the Humber and at Weston. 

 It occurs, commonly, in a fragmentary state.* 



We next take the Mollusca. Beginning with the Cephalopoda, 

 we have the family of the Orthoceratidts. The Orthoceras was a long 

 straight shell, as its name indicates, with a tube running from end to 

 end called the siphuncle. The shell is divided transversely into cham- 

 bers by simple septa. Of this genus we have Orthoceras coralliferum 

 (Hall), and Orthoceras lamellosum (Hall). The so-called genera 

 JEndoceras and Ormoeeras are also found at Milton up the Humber. 

 The siphuncle of Endoceras is said to be made up of funnel-shaped 

 diaphragms, and is very large. The same organ in Ormoeeras is 

 lieaded. These distinctions as generic characters do not now hold 

 good ; and Endoceras and Ormoeeras, with some other genera are 

 included in the genus Orthoceras. 



The Gasteropoda next claim our attention, Cyrtolites ornafus 

 (Conrad), a very beautiful shell, is excessively common at Weston, 

 and indeed at all the localities mentioned above. Murchisonia gracilis 

 (Hall) the most common of the Murehisonias, (a genus named after 

 Sir Roderick Murehison), is found in a good state of preservation at 

 Weston. Pleurotomaria suhconica (Hall) is rather rare. It is found 

 at Weston, and also at Toronto. A beautiful specimen of P. bilix 

 (Conrad), retaining the shell and epidermis or colouring, was found in 

 Toronto. f Bellei'ophon eancellatus (Hall) is very rare, only two or 

 three specimens having been met with in this neighbourhood- 

 No Pteropods have yet been discovered here. 

 The Brachiopoda come next in order, and are extensively repre- 

 sented. The most characteristic are : Leptasna sericea (Sowerby), and 

 L. alternata (Conrad), both very common at Weston and other places. 

 Atrypa increbescens (Hall), is comparatively rare. Lingula quadrata 

 (Eichwald), has been discovered at Weston badly preserved. The 

 shell has the dark, polished aspect, so characteristic of the Pcdceozoic 

 lingulcB. Orthis testudinaria (Dalman), a fossil distributed widely 

 throughout the Lower Silurian system. Orthis erratica (Hall) is also 



• To these Trilobitx's we may add Trinucleus concentricus, discovered quite recently in 

 the neighbourhood of Toronto by one of our Students, Mr. William Brown, of Cobourg. 

 C. W.— [E. J. C. 



+ By the late much lamented Mr. John Head, the only son of his Excellency Sir E. "W. 

 Head, Bart., whose early loss, at the commencement of a career so rich in scientific promise, 

 cannot be too deeply deplored. The Editors of the Canadian Journal join most sincerely 

 in this expression of regret- 



