(116) 



strongly involute. Articulations pellucid, below the middle three to four 

 times longer than broad, very short upwards, those in the apices scarcely 

 apparent ; dissepiments opaque, scarcely swollen, furnished in the middle 

 with a whorl of from six to eight stout, pellucid, three-jointed sjDines, all 

 regularly pointing upwards, the two upper joints very small, the basal 

 one very large and contracted at the base. Substance rather rigid, very 

 imperfectly adhering to paper in diying. Colour, a rather dark purplisli 

 red, soon changing to pale reddish purple and reddish white in decay. 

 Favellse " roundish, lateral, nearly sessile, and accompanied by three 

 or four short, incui-ved ramuli." — D'dhvyn in Phyc. Bj-it. Tetraspores 

 " not very prominent, disposed in a whorl round the joint, alternately 

 with the prickles." — Phyc. Brit. Both seem to be rare, as we have seen 

 neither. 



The name of the present species has long formed a recejitaele for 

 the greater part of the ciliated and even spinous species of Ceramia, 

 several of which are now pretty clearly distinguished as species. Fi'om 

 C. echionotum it is readily known by its regular whorl of erect, three- 

 jointed, not scattered, squan-ose, single-jointed spines, and from C. acaii- 

 thonotum by the single erect spine on each of the dissepiments of that 

 species. Tlie habit of the three species is much the same, as well as 

 that of C. strictum and nodosum ; they have therefore been denominated 

 " cabinet " species, as their characters are not readily apparent to the 

 naked eye, and only become perceptible when submitted to the analysing 

 powers of the microscope. 



The present species does not seem to be abimdant in many places, as 

 we have rai'ely met with it, and never in plenty, and few of our coiTe- 

 spondents seem well acquainted with it. Both kinds of fruit appear to 

 be rare. 



EXPLANATION OF PLATE CVIIL 



Fig. 1. — Ceramhim ciliatum, natural size. 

 2. — Apex of a branch. 

 3. — Joint ■with tetraspores. 

 4. — A tetraspore from same. 

 5. — Joint with cilias. All magnified. 



