No. 7,] WHITEAVES — SIPIIONOTRETA & IIETEROPORA. 397 



Upper Llandeilo of Craighead, nor do I see any in your speci- 

 mens. As there is uncertainty as to the specific identity of the 

 highest Upper Silurian form with the Lower Silurian one, and 

 as none have been found in all that mass of intervenius; strata, 

 I prefer provisionally to retain the two names, or until other 

 Upper Silurian species shall have been found." 



/S. Scotia was originally described and figured in the Geo- 

 logical Magazine for January, 1877, and if the Canadian speci- 

 mens are specifically identical with those from Scotland, the 

 species must have had a considerable range in time, for the 

 Upper Llandeilo rocks are generally regarded as of about the 

 same age as the Chazy Limestone of the State of New York, and 

 the Utica Slate as corresponding to beds on a comparatively high 

 horizon in the Caradoc or Bala Group. To the palaeontologist 

 Mr. Watt's discovery will be of special interest, as this is the 

 first time that the occurrence of a species of Siphonotreta in 

 North America has been placed upon record. 



ON A RECENT SPECIES OF HETEROPOKA FROM 

 THE STRAIT OF JUAN DE FUCA. 



By J. F. White AYES, F.G.S. 

 (Read before American Association for Advancement of Science, Montreal, 1882) 



The genus Hcteropora was constituted by De Blainville in 

 1830, for the reception of a number of fossil species of Polyzoa 

 of the order Cyclostomata, whose characters are thus defined by 

 Busk : — " Polyzoarium erect, cylindrical, undivided or branched ; 

 surface even furnished with openings of two kinds ; the larger 

 representing the orifices of the cells, and the smaller the ostioJes 

 of the interstitial canals or tubes." •' The essential character of 

 the genus," writes Dr. H. A. Nicholson, "is thus the possession 

 of a skeleton made up of two kinds of tubes, larger and smaller, 

 the latter beiu"; the most numerous." Further, it has been 

 ascertained that the tubes of Hetevopora are provided with cross 

 partitions and radiating spines, and that their walls are perfor- 

 ated by numerous openings. These structures have been held to 

 be the homologues of the tabula) and septa of the tabulate corals, 

 and of the mural pores of the Favositida3. Lindstrom, in 187<j, 

 maintained that the Palaeozoic fossils known to i^-eolouists as 

 Chcptefes. Stenopora and Monticulip)ora have almost exactly the 



