316 Annals of the South African Museum. 



Hyatt's genus Cheloniceras is adopted for these Aptiau forms since 

 the sreuus Douvilleiceras should be restricted to the Albian mammillatum 



o 



group. According to Kilian* the group of " Douvilleiceras " royeri- 

 anum, d'Orbigny sp. (= type of Cheloniceras), is closely connected 

 with the martini and albrechti-austriae groups (to which last the 

 form here described belongs), and not with the group of " D." bigoureti, 

 which " leads to Acanthoplites." The relations of these Aptian forms 

 with the Barremian Paraspiticeras have yet to be worked out. Sinzowt 

 would include the type of Paraspiticeras (P. percevali, Uhlig sp.) 

 Avith the Aptian Ch. meyendorffi, d'Orbigny sp.,+ but in the writer's 

 opinion the two developments are distinct. 



3. CHELONICERAS (ACANTHOPLITES ?) DELAGOENSE, Krenkel sp. 



(PI. XXVI, figs. 2 a-d.-) 



1910. Douvilleiceras delayoense, Krenkel. " Aptfossil. d. Delagoa 

 Bai," N. Jb. f. Miu., etc. (i), p. 147, pi. xvii, figs. and 7. 



A small example (No. 5118), shoAving very good agreement Avith 

 Kreukel's species, by its suture-line belongs to the same group of 

 forms as the specimen last described, but in loss of tuberculatiou, and 

 in the costatiou of the outer whorl, one-third of which already belongs 

 to the body-chamber, it has a superficial resemblance to the genus 

 Acantlioplites. The dimensions are as follows : 



Diameter . . 22 mm. 



Height of the last Avhorl . 37 per cent, of the diameter. 



Thickness ,, 48 ,, ,, 



Umbilicus ... 40 



At a diameter of 7'5 mm., at Avhich the suture-line represented in 

 fig. 2 c Avas taken, the whorl-section is depressed, and there are con- 

 strictions as in Cheloniceras roijerianum, d'Orbigny sp., and in the 

 specimen last described. The point of bifurcation of the ribs is 

 marked by a tubercle at this stage, as in Cheloniceras seminodosum, 

 SinzoAV sp., or in Acantlioplites Bigoureti (Seunes), Jacob, || and the 



* Loc. cit. (1913), p. 340. 



f Loc. cit. (1906), p. 163. 



J See also 'Pal. Univ./ 1911, pi. ccix. 



" Beschr. eiuiger Douvilleiceras-Arten a. d. Ob. Neocom. Eussl.," ' Verh. 

 Kuss. Kais. Mineral. Ges.' (2), vol. xliv (1906), p. 165, pi. i, fig. 3 only. 



|| " Gisement de Clausayes," ' Bull. Soc. Geol. France ' (4), v, pi. xiii, 

 figs. 6 a, b. 



