ASYMPTOCERAS FOOHDI. 



25 



of the periphery, repeating a similar curve on the other side. On the wall of the 

 umbilicus the impression runs nearly parallel with the basal edge of the body- 

 chamber. 



The chambers are moderately deep. The last six (leaving the body-chamber 

 out of account) give the following measurements,^ No. 1 in the table repre- 

 senting the last chamber, No. 2 the penultimate, and so on. 



[Note. — The measurements are taken at about the middle of the lateral area. 

 See PL XXXTI, fig. la.] 



1 .... . 13-0 mm. 



2 

 3 

 4 

 5 



16-6 

 14-0 

 13-5 

 10-5 



The siphuncle traverses the margin of the periphery in the median line (PI. 

 XXXII, figs. I h and 2). 



The test is perfectly smooth except upon the apertural inflation, where there 

 are lines of growth in the shape of faint ridges regularly disposed, and having a 

 curvature which corresponds with that of the margin of the aperture. 



Dimensions. 



Large Specimen I'rora Chine, iu 

 Science and Art Museum, Dublin. 



. 149 



mm 



. 49 





. 25 





. 84 





. 92 





. 82 



• 1 





Diameter of shell 



„ umbilicus (edge to edge) 



„ ,, (suture to suture) 



Height of whorl (dorso-ventral) 



Thickness at centre of lateral area (without test) 

 „ aperture 



Affi.nities. — The relationship between the present species and Asymptoceras 

 crassilahrum, Foord, has been pointed out above in the description of the latter. 

 It is more nearly related to A. conspicuiiui, de Kon.," sp. But the latter, as 

 observed by Hyatt,^ is not so closely coiled, nor is the body-chamber produced 

 beyond the earlier part of the last whorl, as in A. Foordi. The sutures also are 

 more numerous and more sinuous in de Koninck's species than they are in 

 Hyatt's. 



1 Mr. Gr. C. Crick kindly supplied me with these measurements from the specimen in the 

 British Museum, which I have figured. 



" ' Faune Calc. Carb. Belg.,' pt. 1, p. 109, pi. xix, figs. 1 a — e ; pi. xx ; pi. xxi, figs. 1 a, b. 



2 ' Carboniferous Cephalopods. Second paper. Geological Survey of Texas, Fourth Annual 

 Eeport,' 1892, p. 459. 



19 



