MIOROGROMIA. 129 



Test small, hyaline, spherical or pyriform, not com- 

 pressed ; aperture circular, terminal ; pseudopodia 

 long, straight or branching, filose or anastomosing, 

 usually arising from a peduncle ; nucleus single ; one 

 contractile vesicle usually present; habit solitary or 

 colonial. 



M. socialis and M. mucicola, the two species recorded 

 from Great Britain, often occur in colonies or small 

 groups, and in this state may be joined by a pseudo- 

 podial reticulum, but when they are solitary the 

 pseudopodia are filose ; in either case they arise from 

 a peduncle. M. elegantida Penard also possesses a 

 peduncle and filose pseudopodia. M. levipes Penard is 

 similar but apparently has no peduncle.- The genus is- 

 therefore somewhat anomalous and is intermediate in 

 character between the Pseudo-gromiina3 and the Allo- 

 gromiinse, and might perhaps with equal propriety be 

 placed in either family. 



SYNOPSIS OF THE BRITISH SPECIES. 



Test small; often found in large colonies. (1) M. socialis. 

 Test minute ; habit usually solitaiy ; when in groups these 

 consist of two or three individuals only. 



(2) M. mucicola. 



1. Microgromia socialis (Archer) Hertwig & Lesser.. 

 (Plate LV ; PL LVI, figs. 1-6.) 



Difflugia enchelys 



SCHNEIDER in Arch. Anat. PhysioL XXI (1854), pi. ix, ff. 17-21. 



(Non Ehrenberg, 1838.) 

 Arcella hyalina 



FRESENIUS in Abh. senckenb. nat. Ges. II (1858), pp. 219-223, pi. xxii, 



ff. 1-24. (Non Ehrenberg, 1838.) 

 Gromia socialis 



ARCHER in Qrt. Jra. Micr. Sci. (N. s.) IX (1869), pp. 322, 390 ; op. cit. 

 (N. s.) X (1870), pp. 22, 124, pi. xx, ff. 7-11 ; in Proc. Dubl. Micr. 

 Club, I, 5 (1872), pp. 289, 344, 349, 392, pi. xiii, ff. 7-11. 

 SCHULZE in Arch. mikr. Anat. XI (1875), pp. 118-122, pi. vi, ff. 



21-26. 

 G-RUBER in Zeits. wiss. Zool. XXXVI (1881), pp. 115, 123, pi. iv, 



ff. 21-26. 



LANESSAN Protozoa (1882), p. 62, ff. 47-50. 

 VOL. III. 9 



