1858.] MimcHisoN — northern highlands, etc. 381 



series (see fig. 5. p. 368). They are known under the name of Are- 

 nicolites. Fig. 30 is a side-view of the contents of the burrow, and 

 is trumpet-shaped above and striated on the sides. 



Fig. 31. Serpulites Maccullochii, new species. (See ' Siluria,' new 

 edit. p. 222.) Short, subcorneal, and curved tubes, of thick sub- 

 stance, and with but a slender central perforation. They were pro- 

 bably quite free, living in sand as does the recent Ditrujja, to which 

 they are not unlike, except in the great thickness of the shell. 



ZOOPHYTA. 

 There are fragments of two Corals — one of the Millepore group, 

 and one probably a cup-coral, but too imperfect to identify ; and 

 many of the shells seem to be invested with a Sponge resembling the 

 Stivmatocerium rugosum of the Canadian rocks. 



Note on the Fossils. — It will be observable, on glancing over the 

 previous Hst, that the identifications with American fossils are not 

 in many cases complete — certainly not so much so as a more cursory 

 examination at first induced me to believe. And it may perhaps be 

 that some of those here positively identified with species of the lower 

 limestone of America may prove to be representative forms only when 

 more perfect specimens can be compared. For example, Orthoceras 

 TYiendax merely resembles 0. multicameratum, Hall. 0. vertebrale is 

 but a doubtful identification, from imperfect specimens. Oncoceras, 

 though of a different species, is an American genus. Euomphalus 

 matutinus and Raphistoma lahiata, if not identical, are at all events 

 representative forms. Maclurea Peachii, Murchisonia angulo-cincta, 

 and Pleurotomaria Thule, though new species, are closely allied to 

 American forms. 



On the other hand, there appear to be some, of the identification 

 of which there cannot be much doubt : such as Orthoceras arcuoli- 

 ratum, Hall. 0. undulostriatmn of our lists differs very little from the 

 species so called. Orthis striatula is truly identical. Ophileta com- 

 pacta and Murchisonia gracilis, with M. belUcincta, are others which 

 I cannot separate from American species. 



There are, then, Jive identical, three doubtful, four which may 

 fairly be called representative forms (the Maclurea, the Orthoceras, 

 Murchisonia angulo-cincta, and Pleurotomaria) ; and Piloceras is a 

 new genus, found in Canada* and in Scotland. 



That this truly North American assemblage should be found in 

 the extreme north of Scotland, on the same parallel as the Canadian, 

 — ^that species of Maclurea and Raphistoma, resembling those of the 

 St. Lawrence basin, and OrtJiocerata bearing large siphuncles like 

 those of N. America, Scandinavia, and Eussia, should occur in Scot- 

 land, and yet be scarcely known further south, is at least suggestive 

 of a geographical distribution — perhaps even of climatal conditions 

 — ^not very unlike that of more modern times f. — J. W. S. 



* The Canadian species is distinct. 



t See the generalizations on this head, ' Siluria,' new edit. pp. 182, 507, et seq. ; 

 and Appendix, p. 553. 



