ATLAS DER DIATOMACEEN-KUNDE. 
7,9 
Aulacodiscus circumdatus^ Schmidt, n. sp. 
„ fo7'7nosus, Arnott. 
„ mjlatus, Greville. 
,, quad7^ans, Schmidt, n. sp. 
„ Johnsoni^ Arnott. 
„ Ehrenhergii^ Janisch (nach Kitton=A. Kit- 
toni^ Arnott). 
,, KittoTii, var. 
„ Kittoni = A. Icevis, Brightwell. 
„ B7ightwelli, Janisch. 
„ excavatus, Schmidt, n. sp. 
,, sparsus, Greville (perhaps A. Beeverice, John- 
son). 
„ Comheri, Kitton (This is an error ; Arnott is 
the author.) 
„ p7^obabiUs, Schmidt, n. sp. 
„ suspectus, Schmidt, n. sp. 
„ septus, Schmidt, n. sp. 
„ marqa7'itaceus and vars. 
„ sp.(f) 
„ sp. (?) 
„ sp. (?) 
The five plates contain sixty-four figures, representing twenty- 
nine species. These figures, although faithful likenesses, scarcely 
do justice to this beautiful genus. Figure 14, Tafel 33, A. Mol- 
lerii, is probably C7'ux, of Ehrenberg, see Microgeologie, Tafel 
xviii., fig. 47.* We have found this form with four and five pro- 
cesses. Figure 6 Tafel 34 is doubtless the same form, with four 
processes. The figures of A. Petersii and its variety f are too 
faint ; the figure of the latter is much inferior to that given in the 
specimen plate. Of A. fo7miosus we have two figures — one 
enlarged to 200 diamaters — but like A. Petersii var. is too faint ; 
the second represents a portion of a valve magnified 600 diameters, 
but does not shew the markings between the granules. These 
figures will easily enable the student to recognise the species, but 
they do not give a good idea of the beauty of this form. A. cWcum-^ 
datus appears to us to be only a form of A. Petersii. A. JohnsoTiii — 
this is the form figured in the Quekett Journal, No. 31, p. 149, by 
Mr. Cottam, as A. afidcanus, n.s. It differs somewhat from the form 
found in the Algoa Bay guano. A. Ehrenhergii is the same as A. 
Kittoni. A. Bidglitwellii is only A. Kittorii, with six processes. 
Herr Janisch, in his “ Zur Characteristik des Guanos von Yer- 
schiedener Fundorten,” p. 15, says — ‘‘A. B7nghtwellii, C. J., wie 
f This form was found in the “ Eichmond deposit,” and is identical with 
that occurring iAthe “ Nottingham deposit,” the form in Tafel xxxv.a. xvi., 
fig. 2, foimd in Peruvian guanoy and is doubtless the same as A. crux, 
Janisch = A. scaher, Ealfs. 
f This variety is probably the same as A. 3Iac7'csanus, Greville (Trans. 
Micro. Soc., Vol. x. n.s., pi. 2, fig. 4). 
