84 DUBLIN" NATtrilAL HISTORY SOCIETY. 



truncate ; endochrome at first a single, rather closely wound spiral band, 

 its revolutions few, frequently afterwards scattered and indistinct, in 

 each fully grown frond, leaving at each end a minute semicircular clear 

 space, in which there occur one, or perhaps two, free granules ; gela- 

 tinous investment very evident. 



Measurements : — Length of frond j^q ; breadth, gj^^ of an inch. 



Plate II., Figs. 28, 29, mature frond; Fig. 30, 31, two recently 

 divided fronds, all magnified 400 diameters. 



Affinities and Differences: — The cylindrical frond tapering towards 

 the ends in this species renders it somewhat like in outline to that of 

 8pirot(Bnia olscura (Ralfs), with which it also agrees in having a clear 

 space containing often one, occasionally two, or even three free gra- 

 nules ; but it diifers from that species in its greatly more minute size, in 

 its truncate, not broadly rounded ends, and in its endochrome forming a 

 solitary, not several spiral bands. With 8. condensata (Breb.), S. musci- 

 cola (De Bary), and 8. erythrocepJiala (Itzigsohn), it agrees in its single- 

 spired endochrome ; but its tapering truncate ends well distinguish it 

 from the broadly rounded ends of the two former, and from the acute 

 ends of the latter, besides other characters in each instance, as is readily 

 seen by the foregoing description. From Entospira closteridia (Breb.), 

 — a species which I apprehend ought to be referred to the genus Spiro- 

 tsenia — this form is distinguished by its larger size, by its straight and 

 cylindrical, not arcuate or sublunate, outline, as well as by its truncate 

 ends and terminal clear space. Its larger size, truncate ends, and broad 

 spiral band, readily separate this from the following new species : — 



8pirotenia parvula (sp. nov,). 



Specific Characters : — Frond very minute, slender, fusiform, ends 

 sub-acute ; endoclu'ome obliquely parietal, scarcely spiral. 



Locality : — Featherbed Bog, Dublin Mountains, in Sphagnum pools, 

 on the moss. IN'ot unfi'equent, but readily overlooked on account of its 

 very minute size. 



General Description : — Frond very minute, five to eight times longer 

 than broad, fusiform, ends sub-acute ; endochrome a single oblique pa- 

 rietal band, often scarcely forming a spire, but frequently presenting to 

 view apparently three darker portions of elongate form, one towards 

 each end at the same side of the frond, the other at the middle at the 

 opposite side, thus leaving between them a very narrow eccentric curved 

 clear space ; gelatinous investment of great tenuity, and rendered evi- 

 dent only by preventing the contact of foreign bodies, and by holding 

 together the recently divided fronds. 



Measurements : — Length of frond, ^^ to j^q ; breadth, j-^q-q to 



Tono of ^^ i^c^- 



Plate II., Figs. 32 to 43, mature and recently divided fronds, all mag- 

 nified 400 diameters. 



Affinities and Diff'erences: — The scarcely spiral, sometimes scat- 

 tered endochrome, at first made me hesitate to consider this plant as be- 



