44 Dr. H. A. Nicholson on the Minute Structure 
equal in length. Thorax with its sides obliquely diverging 
from the base to beyond the middle, thence rounded and con- 
verging to the apex, the latter abruptly constricted. 
Cephalodonta Haroldi. 
Cuneiformis, subdepressa, nitida, subtus nigra, thoracis lateribus, 
femoribus tibiisque rufo-fulvis ; supra lete rufo-fulva, antennis 
nigris, articulis rufo variegatis ; thorace subquadrato, lateribus 
obsolete angulatis, angulis anticis antrorsum productis; disco 
transversim convexo, ante basin transversim depresso, profunde 
foveolato-punctato; elytris a basi apicem versus leviter ampliatis, 
apice obtusis, leviter serratulis, angulo postico distincto, profunde 
foveolato-punctatis, punctis striatim dispositis, hic illic confusis, 
interspatiis ad latera et ad apicem elevato-vittatis, hic illic irregu- 
lariter verrucosis. 
Long. 33-33 lin. 
Hab. Columbia, river Magdalena. 
Nearly allied to C. tarsata, at once known by the coarser 
punctuation and by the irregular surface of the elytra. 

VI.—On the Minute Structure of the Corals of the Genera 
Heliophyllum and Crepidophyllum. By H. ALLEYNE 
Nicuotson, M.D., D.Sc., F.L.8., Professor of Natural 
History in the University of St. Andrews. 
Genus HELIOPHYLLUM*. 
Heliophyllum, Hall, in Dana’s ‘ Zoophytes,’ Explor. Exped. vol. viii. 
p. 356, fig. 3, 1846. 
Gen. char. Corallum simple or compound, usually turbi- 
nate, cono-cylindrical or cylindrical, rarely massive. Increase, 
in the simple forms, by simple calicular gemmation. Epitheca 
complete, thin, with encircling striz and annulations of growth. 
Tabule not complete, but confined to a more or less exten- 
sively developed central area. Septa well developed, of two 
orders, a greater or less number of the primary septa almost 
always passing inwards to the centre of the visceral chamber, 
where they become flexuous and unite with one another in 
an irregular network. In cross section the septa are invari- 
ably crossed by conspicuous cross bars or denticulations. 
* Descriptions of the characters of Heliophyllum and Crepidophyllum 
formed part of a paper, by Mr. James Thomson and myself, which was 
laid before the Royal Society of Edinburgh in the session 1875-76, and 
an abstract of which was published in the ‘ Proceedings,’ vol. ix. No. 95, 
p. 149. 
