DUBLIN MICKOSCOPICAL CLUB. 341 



tation of foreign particles, possessing, as it did, two opposite 

 stomata at either end of an elliptic test, for emission of rhizo- 

 podous paeudopodia, would fall under his own genus Amphitrema. 

 Drs. Hertwig and Lesser, in their very thorough treatise on fresh- 

 water Rhizopoda^ proceed throughout on the principle of separat- 

 ing otherwise kindred forms into distinct (collateral) genera, de- 

 pendent on the character as to the test being a pure secretion- 

 product or being incrusted with foreign mineral particles or 

 diatomaceous frustules and fragments, &c. — a principle which 

 Mr, Archer, so far as he could see, had felt altogether called 

 upon to approve. But, in respect to the present new form, 

 coming away from the incrusted Amphitrema across the line 

 so drawn, the only other established genus of Amphistomatous 

 Ehizopods was Dr. Barker's Diplophrys. Still no one, viewing the 

 two or, including DiplopJirys Archeri, three organisms, could 

 arrive at any other conclusion than that the new one now ex- 

 hibited was really by far more closely and naturally allied to 

 Amphitrema Wriglitianum than to Diplophrys Archeri — in fact, 

 to refer the new form to Diplophrys would surely be artificial 

 in the highest degree, keeping Amphitrema in view. But if not 

 to be referred to the latter genus on account of the test being 

 quite bare of foreign particles, in fact, absolutely smooth and 

 glossy, there would be nothing for it but a new genus bearing 

 a relationship to Amphitrema comparable to that of Plagiophrys, 

 Clap, et Lachm., to Pleurophrys, Clap, et Lachm. In the new 

 form the stomata were very sharply marked openings, with a 

 slightly developed rim projecting somewhat inwards and with a 

 perfectly " clean " edge ; test smooth and glossy, quite without 

 any markings and of a yellowish colour, of a somewhat thick 

 and rigid character. Mr. Archer exhibited side by side with the 

 new form some examples of .^mp/i^Yrewja Wrightianum, which he 

 had had for some time by him treated with Beale's carmine fluid, 

 showing the nucleus half way between the two openings, the 

 test however had become in itself very pellucid and its brownish 

 colour gone. This seemingly decidedly rare species he had taken 

 only on some half dozen occasions, but the stations wide apart — 

 some from Glen-ma-lur, Co. Wicklow, some from Co. West- 

 meath, some from Co. G-alway, some from Co. Kerry, and these 

 (as well as the new form) from " Tooles Eocks," Co. Wicklow. 

 It is seemingly remarkable that as yet Amphitrema Wrightianum, 

 has not been found on the continent, notwithstanding the 

 recent very active researches by various observers in this field, 

 and it was perhaps a curious coincidence that Mr. Archer should 

 likewise be the first to encounter a second, or rather counting 

 Diplophrys, a third amphistomatous form, whilst the latter (D. 

 Archeri, which has now a companion in D. stercorea, Cienk. — an 

 unsavoury propinquity in which to find one's self!) most puzzling 



* Hertwig and Lesser : " Ueber Rhizopoden und denselben nahestehende 

 Organismen" in Schultze's ' Archiv f. Mikrosk. Anatomie,' Bd. x (1874). 



