Dugald Bell— Notes on Glen Rot/. 319 



one vow of primary tubercles in each series of interambulacral plates, 

 instead of several series. 



The only Ecbinoid known to me, in addition to the type species, 

 which may be referable to this genus is one figured by Quenstedt 1 as 

 Echinopsis nattheimensis, which Desor and De Loriol-Lefort 2 have 

 refigured as a Hemipedi.ua. The figure of the latter authors shows 

 the pore-pairs in a single series to the peristome, and if this be the 

 case, then the species must enter the new genus. But these authors 

 also showed some species, such as Uemipedina elegans (Des.), with 

 the same character ; and these, according to the more detailed figures 

 of Cotteau, 3 have the normal arrangement of Uemipedina. 



The small size and primitive characters of the specimens render it 

 necessary to consider whether they are only young Diademopsis ; but 

 the specimens seem to be fairly abundant, and yet are generally of 

 about the same size ; the whole appearance of the Echiuoids suggests 

 that they are adult. 



Arch^eodiadema Thompsoni, n.sp. (See Woodcut, p. 318.) 

 Diagnosis. — Test small, turban-shaped ; sides tumid ; abactinal 

 half depressed ; actinal half somewhat conical ; circular. 



Apical system large, regularly pentagonal; arrangement unknown. 

 Ambulacra narrow, inconspicuous. About four fair-sized primary 

 tubercles in a vertical row on the ambitus; these gradually 

 decrease into small secondary tubercles above and below. 

 Interambulacra of vertical series of from six to nine plates ; the 

 scrobicular circles are complete above, but incomplete at the 

 ambitus. There is one row of primary tubercles, and the 

 number of granules is small ; these mainly occur in a band 

 down the middle of interambulacrum. 

 Peristome large, circular, with conspicuous branchial slits. 

 Dimensions. — Diameter, 6 mm. ; height, 3 mm. ; diameter of 

 apical area, 3 mm. ; diameter of peristome, 3 mm. ; width of ambu- 

 lacrum at ambitus, 1 mm. ; width of interambulacrum at ambitus, 

 3 mm. ; number of primary ambulacral plates in vertical series, 19 ; 

 number of interambulacral plates in vertical series, 7. 



Distribution. — Cerithium beds or Lower Leda ovum beds 4 of Upper 

 Lias : Higham Ferrers, Northamptonshire. — British Museum Coll. 

 Presented by Beeby Thompson, Esq., F.G.S. 



VII. — Notes on Professor Bonnet's "Ice-Work." — Glen Pot. 

 By Dugald Bell, F.G.S. 



BESIDES his numerous papers intended for experts in geological 

 science, Professor Bonney is to be congratulated on the 

 lengthening list of his more popular writings on the subject. 



1 Quenstedt, " Handb. d. Petref.," 1852, p. 582, pi. xlix, fig. 37; also in 

 "Petrel'. Deutsch.," Bd. iii, 1874, p. 349, pi. lxxiv, figs. 10, 11. 



2 Desor and De Loriol, " Eebinol. helvet.," 1871, p. 194, pi. xxxiii, fig. 3. 



3 Cotteau, "Pal. franc,. Terr, jurass.," t. x, pt. 2; " Eehinides reguliers," 

 livr. ii, 1883, pi. cccxciii. 



4 Beeby Thompson, "The Upper Lias of Northamptonshire," part vi : Journ. 

 Northampton Nat. Ilist. Field Club, vol. v, 1888, p. 54 ; the section is described 

 on p. 63. 



