ARCELLA CATILNUS. 15 
Isles it is somewhat rare, although it is sometimes 
numerous in the localities where it does occur. 
Cash in his description and figure has omitted the 
pores which surround the oral aperture and are usually 
about twelve in number. 
It is quite distinct from A. artocrea Leidy, although 
Penard referred it to that species in his ‘ Faune Rhiz. 
du Léman’ (1902) thinking it might be a European, 
Fia@. 163.—Arcella catinus. Upper and lateral views. x 260. (After 
Cash.) 
| form of it, but A. catinus in its typical form, as drawn 
by Leidy (Pl. xxvin, figs. 6 and 7) and Cash, is not 
uncommon in America. 
3. Arcella arenaria Greeff. 
(Plate LVITI, figs. 4 and 5.) 
Arcella arenaria 
GREEFF in Arch. mikr. Anat. II (1866), p. 330, pl. xviii, f. 16; in 
Sitzb. Ges. Marburg, 1888, pp. 106-107. 
LAGERHEIM in Geol. Féren. Stockholm Forh. XXXTIIT (1901), p. 507. 
LEVANDER in Acta Soc. Fauna Fenn. XX (1901), p. 7. 
Prenarp Faune Rhiz. Léman (1902), pp. 406-408, 3 figs.; in Arch. 
Protist. IX (1903), p. 258; Sarcodinés in Cat. Invert. Suisse (1905), 
pp. 79-80; in Deux expéd. Antarct. francaises (1911), pp. 4, 5. 
AVERINTZEFF in Trudui S.-Peterb. Obshch. XXXVI, 11 (1906), pp. 
159-160. 
ScHOUTEDEN in Ann. Biol. lacustre, I, 3 (1906), pp. 335-336. 
Brown in Naturalist, 1910, p. 93; in. Brit. Assoc. Handb. Sheffield, 
(1910), p. 500; in Scott. Natur. 1912, p. 112; op. cz#. 1913, p. 146. 
Dapay in Sitzb. Akad. Wien, CXIX, 1 (1910), p. 575. 
CocKERELL in Univ. Colorado Stud. VIII, 4 (1911), p. 241. 
