l AMPH1TREMA FLAVUM. 149 



cially in upland districts. The average size of British 

 individuals (55-70 ft in length) appears to be greater 

 than that of the Swiss (45-55 /z: Penard), but in the 

 United States the size is about the same as in the 

 British Isles. 



A noticeable peculiarity of this species is the 

 apparent tendency of individuals to divide into halves 

 transversely (vide Penard, ' Faune Rhiz. Leman '). 

 At Leckby Carr near York, where this species occurs 

 numerously, many individuals as shown in Plate LVI, 

 fig. 4, were seen, but in no case had the division pro- 

 ceeded beyond the depicted stage. 



In Mayo this species was found by Penard contain- 

 ing spherical blue-green algae (4 /x dia.) which were 

 not Chlorella vulgaris (Beyerinck), the species usually 

 found living symbiotically with Rhizopoda. 



2. Amphitrema wrightianum Archer. 

 (Plate LVII, figs. 6-8.) 



(Allied to Actinophrys or Acineta 



BRIGHTWELL Fauna Infus. E. Norfolk (1848), p. 24, pi. xi, f. 3.) 

 Amphitrema wrightianum 



ARCHER in Qrt. Jrn. Micr. Sci. (N. s.) IX (1869), p. 397, pi. xx, ff. 



4, 5 ; op. cit. (N. s.) X (1870), pp. 20-21, 122, pi. xx, ff. 4, 5 ; (N. s.) 



XVI (1876), p. 341 ; in Proc. Dubl. Micr. Club, I, 5 (1872), pp. 



355-356, 390-391, pi. xiii, ff. 4, 5 ; op. cit. Ill, 2 (1878), p. 132. 

 BUETSCHLI in Bronn's Thierreichs, I, 1 (1880), pi. iv, f. 3. 

 LANKESTER in Encycl. Brit., ed. 9, XIX (1885), p. 16, f. ix (11) ; 



in Zool. Art. contrib. Encycl. Brit. (1891), p. 16, f. ix (11). 

 BLOCHMANN Mikr. Thierw. Siisswass. (1886), p. 16 ; ed. 2 (1895), 



p. 20. 



DELAGE & HEROUARD Traite Zool. concrete, I (1896), p. 116, f. 154. 

 WEST in Jrn. Linn. Soc., Zool. XXVIII (1901), p. 332. 

 CHAPMAN Foraminifera (1902), p. 71, pi. i, f. P. 

 PENARD Faune Rhiz. Leman (1902), pp. 539-540, 3 figs. ; Sarcodines 



in Cat. Invert. Suisse t!905), p. 113. 

 AVERINTZEFF in Truduf S.-Peterb. Obshch. XXXVI, n (1906). p. 95, 



pi. ii, f. 37 ; pp. 320-321 ; in Ann. Biol. lacustre, I (1906), p. 324. 

 SCHOUTEDEN in Ann. Biol. lacustre, I (1906), p. 373. 

 EVANS in Proc. B. Phys. Soc. Edinb. XVII (1907), table 1. 

 HEINIS in Arch. Hydrobiol. V (1907), p. 111. 

 HOPKINSON in Irish Natur. 1910, p. 3. 

 BROWN in Jrn. Linn. Soc., Zool. XXXII (1911), p. 84. 

 HARTOG in Encycl. Brit., ed. 11, XXII I (1911), p. 248, f. 7 (10). 

 WAILES & PENARD in Proc. B. Irish Acad. XXXI, LXV (1911), pp. 



14, 20, 61. 



