l.Vl 



ON A NEW FORM OF CARBONIFEROUS NAUTILOID {AMFHOREOPSIS 

 FAUGIGAMERATA) FROM THE ISLE OF MAN. 



By G. C. Crick, F.G.S. 



Read Uth May, 1904. 



PLATE VIII. 



The Cephalopod forming the subject of the present communication 

 belongs to the collection of Mr. R. Law, F.G.S., to whom I am indebted 

 for the loan of the specimen ; it was brought under my notice by 

 Mr. G. "W. Lafnplugh, of the Geological Survey, and Mr. E. T. Newton, 

 to whom also my thanks are due. 



In his work on "The Geology of the Isle of Man" (Mem. Geol. 

 Survey, United Kingdom), published in 1903, Mr. Lamplugh recognises 

 the following succession of beds (here given in descending order) in 

 the Carboniferous Basin of the south of the island (p. 189) : — 



5. Volcanic Series of Scarlet. 



4. Posidonomya Beds. 



3. Poolvash or Pale Limestones. 



2. Castletown or Lower Dark Limestones. 



1. Basement Conglomerate. 



The Nautiloid described in the present paper was obtained from the 

 Poolvash Limestone, at Poolvash, on the southern coast of the island. 



The fossil is ovoid, having its greatest thickness a little nearer the 

 anterior than the posterior end; it is about 100mm. long, tapers 

 slowly anteriorly, and rather more rapidly posteriorly ; its transverse 

 section is subcircular, the ventro-dorsal and transverse diameters at 

 its thickest part being 47'5 and 48 mm. respectively, so that the fossil 

 is very slightly depressed. It is very gently curved, the outer or 

 ventral surface being a little more convex than the dorsal, and the 

 posterior end of the fossil turned a little towards the less convex or 

 dorsal surface. By far the greater part of the specimen is occupied 

 by the body-chamber, which is filled partly with limestone and partly 

 with calcite ; it is 83 mm. long. The septate part is very short, being 

 only about 17 mm. in length. The test is wanting on the dorsal area 

 and on the greater part of the sides of the body- chamber ; although 

 a large portion of that which is present on the ventral surface is much 

 eroded, the parts that are well preserved show that the test was almost 

 perfectly smooth. The lateral and dorsal portions of the anterior end 

 of the body-chamber are wanting, but a small piece of the peristome 

 preserved on the dorsal surface shows that the aperture was simple 

 («, Figs. 1 and 2). On the anterior part of the internal cast of the 

 body- chamber there is a fairly deep depression {d, Figs. 1, 2, and 4), 



