Sir W. Datcson — T/ie Animal Nature of Eozoon. 545 



Fig. 8. Pinnocaris Lapworthi, R. Etheridge, jun. Concave mould of the outside 

 ot a left valve. From Balclatchie, Girvan. Mrs. Gray's 

 Collection. 



Fig. 9. Pinnocaris Lapworthi, R. Etheridge, jun. 9fl, convex cast of the inside 

 of left valve ; counterpart of, and fitting into, Fig. 8 ; but 

 imperfect at top and side of upper moiety. 9J, outline of 

 edge view ; 9c, outline of end view. From Balclatchie, 

 Girvan. Mrs. Gray's Collection. 



Fig. 10. Pinnocaris Lapworthi, E. Etheridge, jun. Probably a carapace ; showing 

 the right valve, of which the upper part retains the usual 

 black shining test ; and the lower part is the convex cast 

 of the inside of the posterior moiety of the same. From 

 Ardmillan Brae, Girvan. Mrs. Gray's Collection. 



III. — Review of the Evidence for the Animal Nature of Eozoon 



Canadense. 



By Sir William Dawson, C.M.G., LL.D., F.R.S., etc. 

 III. Structural and Biological. 



IN recent years I have been disposed to attacli raore importance 

 than formerly to the general form and macroscopical characters 

 of Eozoon. The earlier examples studied were, for the most part, 

 imbedded in the limestone in such a manner as to give little 

 definite information as to external form ; and at a later date, when 

 Sir William Logan employed one of his assistants, Mr. Lowe, to 

 quarry large specimens at Grenville and Cote St. Pierre, the attempt 

 was made to secure the most massive blocks possible, in order to 

 provide large slabs for showing museum specimens. More recently, 

 when collections have been made from the eroded and crumbling 

 surfaces of the limestone in its wider exposures, it was found that 

 specimens of moderate size had been weathered out, and could, 

 either naturally or by treatment with acid, be entirely separated 

 from the matrix. Such specimens sometimes showed, either on 

 the surfaces or on the sides of cavities and tubes penetrating the 

 mass, a confluence of the laminae, constituting a porous cortex or 

 limiting structure. Specimens of this kind were figured in 1888,^ 

 and I was enabled to add to the characters of the species that the 

 original and proper form was "broadly turbinate with a depression 

 or cavity above, and occasionally with oscula or pits penetrating 

 the mass." The great flattened masses thus seemed to represent 

 confluent or overgrown individuals, often contorted b^' the folding 

 of the enclosing beds. 



There are also in well-preserved specimens certain constant 

 properties of the old calcite and serpentine lagoons. The former are 

 continuous, and connected at intervals, so that if the siliceous filling 

 of the chambers could be removed, the calcareous portion would 

 form a continuous skeleton, while the serpentine filling the chambers, 

 when the calcareous plates are dissolved out by an acid, forms a 

 continuous cast of the animal matter filling the chambei's. This 

 cast of the sarcodous material, when thus separated, is very uniformly 

 and beautifully mammillated on the surfaces of the laminse, and this 



' Geological Magazine, and Museum Memoir. 



DECADE IV. VOL. II. — NO. XII. 35 



