Linnarsson — On the Eophyton Sandstone. 405 



Annelid burrows often have some raised or depressed ribs ; sometimes 

 they are seen to wind between the ribs, now over, now under them. 

 Although the specimens hitherto obtained do not exhibit a complete 

 series of transitions, it is highly probable that the convex and the 

 more horizontally expanded form belong to one and the same species, 

 more especially as Dawson has found two analogous forms of B. 

 Grenvillensis. 



According to Hall and Dawson the allied American forms always 

 occur on the under side of the strata, where these are reposing on 

 shale, and are thus casts of impressions once formed upon the soft 

 clay. Without doubt the same is also the case with the fossil 

 occurring in Vestrogothia, but I have had no opportunity of directly 

 verifying it. 



The genus Rhysophyciis is still one of the least understood ; it has 

 not even been ascertained, whether it be of vegetable or animal 

 origin. Besides, as now defined, it includes objects too hetero- 

 geneous. Thus B. clavatus and suhangulatiis Hall and E. embolus 

 Eichw. seem to have a closer relation to Arthrophycus Harlani 

 (Conrad) Hall, than to the other forms referred to BhysopJiycus. B. 

 dispar differs from B. bilobatus and Grenvillensis, chiefly in the 

 greater regularity of the ribs and of the change of their direction, 

 and in the considerably increased breadth of the longitudinal furrow. 

 In other respects those three species have so much in common, that 

 they must be considered as closely related, and interpreted in the 

 same way. I can find no reason with Hall to refer them to the 

 Algae. If they were of that origin, we might expect to find a stem 

 or axis. Dawson, who has especially examined the B. Grenvillensis, 

 believes the more horizontally expanded form to be the cast of the 

 tracks of some Trilobite, and the convex to be the cast of a hole 

 excavated by the Trilobite for shelter or repose. He therefore alters 

 the generic name into Busiclinites. This interpretation does not 

 seem an unreasonable account of the horizontal form, but it does not 

 explain so well the convex form ; especially since it is difficult to 

 understand how the ribs could have got the direction they have in B. 

 dispar. The further objection that no Trilobites or other Crustacea 

 are found in the lower Cambrian sandstone of Vestrogothia, is of 

 less importance, as from the discoveries already made it is probable 

 that even Trilobites lived when this layer was formed. Salter* 

 thinks the species referred to the genus Bliysopliycus to be short forms 

 of the genus Cruziana of d'Orbigny, ^ and there certainly seems to 

 be a great affinity between the two. D'Orbigny simply refers his 

 Cruziana to the Articulata ; Salter considers it an Annelid tube, some- 

 what coriaceous. D'Orbigny's name has priority. 



On account of its plant-remains the Eophyton sandstone is 

 considered by Professor Torell as probably a freshwater deposit. 

 That this cannot be the case is proved by its also containing 

 Brachiopods. From the frequent occurrence of ripplemarTcs and 

 rain-prints it may be supposed to be a shore-deposit. 

 ^ Bigsby's Thesaurus Siluricus, p. 2. 



^ Voyage dans rArae'rique meridiouale, iii., 2, p. 30, pi. 1, f. 1, 2 ; 1842. — ^Marie 

 Rouault altered the name to Fnena, Bull. Soc. Geol. Frauce, 2 Ser. Vol. vii. p. 729, 



