254 ARCHER, ON A NEW SPECIES OF COSMARIUM. 



Plate XII, figs. 28, 29, mature frond ; figs. 30, 31, recently 

 dmdecl 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 Spirotcenia obscura, Ralfs, with which it 

 also agrees in having a clear space containing often one, occa- 

 sionally two, or even three, free granules ; but it differs 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 S. condensata, Breb., 

 S. muscicola, De Bary, and S. erythrocephala, Itzigsohn, it 

 agrees in its single-spired endochrome ; but its tapering, trun- 

 cate ends well distinguish it from the broadly rounded ends 

 of the two former and from the acute ends of the latter, be- 

 sides other characters in each instance, as is readily seen by 

 the foregoing description. From Endospira closteridia, Breb., 

 — a species which I apprehend ought to be referred to the 

 genus Spirotsenia — 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. 



Spirotcenia parvula, sp. nov. 



Specific characters. — Frond very minute, slender, fusiform, 

 ends subacute ; endochrome obliquely parietal, scarcely spiral. 



Locality. — Featherbed bog, Dublin mountains, in Sphag- 

 num pools, on the moss. Not unfrequent, but readily over- 

 looked on account of its very minute size. 



General description. — Frond very minute, five to eight 

 times longer than broad, fusiform, ends subacute ; endo- 

 chrome a single, oblique, parietal 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 lea\dng between them a very narrow, eccentric 

 curved, clear space ; gelatinous investment of great tenuity, 

 and rendered evident only by preventing the contact of 

 foreign bodies and by holding together the recently divided 

 fronds. 



Measurements. — Length of frond, -;j^ to -y-^Vir s breadth, 

 --jjVo to , „ '„„ of an inch. 



Plate XII, figs, 32 to 43, mature and recently divided 

 fronds. All magnified 400 diameters. 



